I did a little bit of looking and I found this Spiceworks thread. It looks like they were having a similar problem installing roles and features. I'd recommend giving it a look.

https://dell.to/2XJxxUi

There are 100's of keys in there, I'm not sure which ones to remove inside:

 [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\PackageDetect] 

In the CBS logs I see the following: 

Default, start: Absent, applicable: Installed, targeted: Installed, limit: Installed, selected: Default
2020-06-09 21:20:22, Info CBS Perf: Resolve chain started.
2020-06-09 21:20:22, Info CBS FLOW: Entering stage: Resolving
2020-06-09 21:20:22, Info CSI 00000007@2020/6/10:01:20:22.493 CSI Transaction @0x2be777d5d30 initialized for deployment engine {d16d444c-56d8-11d5-882d-0080c847b195} with flags 00000000 and client id 'TI1.30817989_1308192605:2/Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~10.0.14393.0'

2020-06-09 21:20:22, Info CBS Exec: Resolving Package: Microsoft-Windows-BLB-Package~31bf3856ad364e35~amd64~ko-KR~10.0.14393.0, Update: WindowsServerBackup
2020-06-09 21:20:22, Info CBS Exec: Resolving component from existing package; passing NULL manifest path to PinDeployment and hoping things haven't been scavenged.
2020-06-09 21:20:22, Info CBS Exec: Resolving Package: Microsoft-Windows-BLB-Package~31bf3856ad364e35~amd64~ko-KR~10.0.14393.0, Update: WindowsServerBackup, PinDeployment: amd64_microsoft-windows-b..oyment-languagepack_31bf3856ad364e35_10.0.14393.0_ko-kr_f18c3cafe8aa2bb3
2020-06-09 21:20:22, Info CBS Exec: 1 deployments need bulk staging
2020-06-09 21:20:22, Info CBS Perf: Ready for complete Component closure.
2020-06-09 21:20:22, Info CSI 00000008 Performing 8 operations as follows:
(0) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-BLB-Engine-SrvRes-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(1) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-SPP-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(2) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-BLB-CLI-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(3) PrestageComponent: flags: 0 app: (null) comp: wsbcmdlet.resources, version 10.0.14393.0, arch msil, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(4) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-BLB-Engine-Proxy-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(5) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-BLB-Srv-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(6) PrestageComponent: flags: 0 app: (null) comp: Microsoft-Windows-BLB-Engine-Main.Resources, version 10.0.14393.0, arch amd64, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
(7) PrestageComponent: flags: 0 app: (null) comp: blbproxy.resources, version 10.0.14393.0, arch msil, culture [l:5]'ko-KR', nonSxS, pkt {l:8 b:31bf3856ad364e35}
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-spp-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_c063cae820308d91.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-blb-cli-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_f472f60557429b21.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-b..vres-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_d39552a911e55717.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\msil_wsbcmdlet.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_e5cf49c7cb77c3ed.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-b..roxy-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_81d11850dc73d170.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-blb-srv-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_fa74c0ebeccdf3ae.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\amd64_microsoft-windows-b..gine-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_c9b5b7c7f05c89c7.manifest
2020-06-09 21:20:22, Info CBS Exec: Warning - Manifest doesn't exist for: \\?\C:\Windows\Servicing\Packages\msil_blbproxy.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_64341d7cfc36185c.manifest
2020-06-09 21:20:22, Error CSI 00000009 (F) STATUS_OBJECT_NAME_NOT_FOUND #2666# from Windows::Rtl::SystemImplementation::DirectFileSystemProvider::SysCreateFile(flags = 0, handle = {provider=NULL, handle=0, name= ("null")}, da = (FILE_GENERIC_READ), oa = @0xc71d57eb78->OBJECT_ATTRIBUTES {s:48; rd:NULL; on:[138]'\??\C:\Windows\Servicing\Packages\amd64_microsoft-windows-spp-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_c063cae820308d91.manifest'; a:(OBJ_CASE_INSENSITIVE)}, iosb = @0xc71d57ec18, as = (null), fa = (FILE_ATTRIBUTE_NORMAL), sa = (FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE), cd = FILE_OPEN, co = (FILE_NON_DIRECTORY_FILE|FILE_SYNCHRONOUS_IO_NONALERT|0x00004000), eab = NULL, eal = 0, disp = Invalid)
[gle=0xd0000034]
2020-06-09 21:20:22, Error CSI 0000000a@2020/6/10:01:20:22.518 (F) onecore\base\wcp\sil\merged\ntu\ntsystem.cpp(2898): Error STATUS_OBJECT_NAME_NOT_FOUND originated in function Windows::Rtl::SystemImplementation::DirectFileSystemProvider::SysCreateFile expression: (null)
[gle=0x80004005]
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CBS.log to WER report.
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200610011543.log to WER report.
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200610002941.log to WER report.
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200609195550.log to WER report.
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200608205910.log to WER report.
2020-06-09 21:20:22, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200607173110.log to WER report.
2020-06-09 21:20:22, Info CBS Not able to add pending.xml to Windows Error Report. [HRESULT = 0x80070002 - ERROR_FILE_NOT_FOUND]
2020-06-09 21:20:22, Info CBS Not able to add pending.xml.bad to Windows Error Report. [HRESULT = 0x80070002 - ERROR_FILE_NOT_FOUND]
2020-06-09 21:20:24, Error CSI 0000000b (F) STATUS_OBJECT_NAME_NOT_FOUND #2665# from Windows::Rtl::SystemImplementation::CSystemIsolationLayer_IRtlSystemIsolationLayerTearoff::TransferFile(flags = (OpenForBackupIntent|0x00000200), op = 'Copy', odir = NULL, oname = [l:138]'\??\C:\Windows\Servicing\Packages\amd64_microsoft-windows-spp-main.resources_31bf3856ad364e35_10.0.14393.0_ko-kr_c063cae820308d91.manifest', ndir = @0x2be777c65a0, nname = [l:41 ml:63]'0299f84fc53ed6010d00000088489846_manifest', disp = Unmapped disposition: 0)
[gle=0xd0000034]
2020-06-09 21:20:24, Error CSI 0000000c (F) HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND) #2506# from Windows::ServicingAPI::CCSITransaction::ICSITransaction2_AddComponents(Flags = 0, a = @0x2be77f87e50, mp = @0x2be77f88650, disp = 0)[gle=0x80070002]
2020-06-09 21:20:24, Info CBS Failed to add one or more component [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:24, Error CBS Failed to complete component closure [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:24, Info CBS CommitPackagesState: Started persisting state of packages
2020-06-09 21:20:24, Info CBS CommitPackagesState: Completed persisting state of packages
2020-06-09 21:20:24, Info CSI 0000000d@2020/6/10:01:20:24.946 CSI Transaction @0x2be777d5d30 destroyed
2020-06-09 21:20:24, Info CBS Perf: Resolve chain complete.
2020-06-09 21:20:24, Info CBS Failed to resolve execution chain. [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:24, Error CBS Failed to process single phase execution. [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:24, Info CBS WER: Generating failure report for package: Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~10.0.14393.0, status: 0x800f081f, failure source: Resolve, start state: Installed, target state: Installed, client id: DISM Package Manager Provider
2020-06-09 21:20:24, Info CBS Not able to query DisableWerReporting flag. Assuming not set... [HRESULT = 0x80070002 - ERROR_FILE_NOT_FOUND]
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CBS.log to WER report.
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200610011543.log to WER report.
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200610002941.log to WER report.
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200609195550.log to WER report.
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200608205910.log to WER report.
2020-06-09 21:20:24, Info CBS Added C:\Windows\Logs\CBS\CbsPersist_20200607173110.log to WER report.
2020-06-09 21:20:24, Info CBS Not able to add %windir%\winsxs\pending.xml to WER report. [HRESULT = 0x80070002 - ERROR_FILE_NOT_FOUND]
2020-06-09 21:20:24, Info CBS Not able to add %windir%\winsxs\pending.xml.bad to WER report. [HRESULT = 0x80070002 - ERROR_FILE_NOT_FOUND]
2020-06-09 21:20:25, Info CBS Reboot mark cleared
2020-06-09 21:20:25, Info CBS Winlogon: Simplifying Winlogon CreateSession notifications
2020-06-09 21:20:25, Info CBS Winlogon: Deregistering for CreateSession notifications
2020-06-09 21:20:25, Info CBS FinalCommitPackagesState: Started persisting state of packages
2020-06-09 21:20:25, Info CBS FinalCommitPackagesState: Completed persisting state of packages
2020-06-09 21:20:25, Info CBS Enabling LKG boot option
2020-06-09 21:20:25, Info CBS Exec: Processing complete. Session: 30817989_1308192605, Package: Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~10.0.14393.0 [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:28, Error CBS Failed to perform operation. [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:28, Info CBS Session: 30817989_1308192605 finalized. Reboot required: no [HRESULT = 0x800f081f - CBS_E_SOURCE_MISSING]
2020-06-09 21:20:28, Info CBS Failed to FinalizeEx using worker session [HRESULT = 0x800f081f]
2020-06-09 21:20:31, Info CBS Session: 30817989_1433626356 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:31, Info CBS Failed to internally open package. [HRESULT = 0x800f0805 - CBS_E_INVALID_PACKAGE]
2020-06-09 21:20:31, Info CBS Failed to OpenPackage using worker session [HRESULT = 0x800f0805]
2020-06-09 21:20:31, Info CBS Session: 30817989_1433646367 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:31, Info CBS Failed to internally open package. [HRESULT = 0x800f0805 - CBS_E_INVALID_PACKAGE]
2020-06-09 21:20:31, Info CBS Failed to OpenPackage using worker session [HRESULT = 0x800f0805]
2020-06-09 21:20:34, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{7799F1F9-2FB2-47F6-9413-690C2DB530AB}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1486572424 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS Appl: detect Parent, Package: Microsoft-Windows-Server-LanguagePack-Package~31bf3856ad364e35~amd64~ro-RO~10.0.14393.0, Parent: Microsoft-Windows-ServerCore-Package~31bf3856ad364e35~amd64~~10.0.14393.0, Disposition = Detect, VersionComp: EQ, BuildComp: EQ, RevisionComp: EQ, Exist: present
2020-06-09 21:20:37, Info CBS Appl: detectParent (exact match): Parent: Microsoft-Windows-ServerCore-Package~31bf3856ad364e35~amd64~~10.0.14393.0, parent state: Installed
2020-06-09 21:20:37, Info CBS Appl: Evaluating package applicability for package Microsoft-Windows-Server-LanguagePack-Package~31bf3856ad364e35~amd64~ro-RO~10.0.14393.0, applicable state: Installed
2020-06-09 21:20:37, Info CBS External EvaluateApplicability, package: Microsoft-Windows-Server-LanguagePack-Package~31bf3856ad364e35~amd64~ro-RO~10.0.14393.0, package applicable State: Installed, highest update applicable state: Installed, resulting applicable state:Installed
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{346530E9-C39D-4F6E-98C8-694B0F1BD183}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487032796 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{6C051A35-0266-4E27-8C9F-0395E311E348}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487082842 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{6FA2156B-13A0-4496-9DD2-16A1CC1C53C6}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487122879 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{DFDCDAE0-B560-493D-8788-E48255360DB3}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487152903 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{1297BE0B-CE49-47F2-97FA-07E78FDE99E4}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487192936 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{A1183A6D-22AE-48A2-B2FE-9395AE10179F}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487232968 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{C5DA0357-61F8-4639-9434-EA4422329FAC}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487272995 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{ECC70808-A351-4A33-8A23-078394424859}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487313033 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{F9D16C71-6CFD-459F-A23A-7D90FF3AED0E}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487343057 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{9D0B3520-39A5-4254-90AD-AA83CECF3DAE}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1487383089 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{33D6CF13-224E-459B-AD4F-AF8C5E3CC469}, revision: 202
2020-06-09 21:20:37, Info CBS Session: 30817989_1487483165 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{EEB5EC89-B013-4674-97CB-57C585E1B145}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1488944403 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{F9DF8BA4-A141-4A5A-B129-FD0560276743}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1488984384 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS WU creates the package, AppID:UpdateOrchestrator, UpdateID:{23C19DFC-2E24-4535-B32C-70C71BCB357D}, revision: 201
2020-06-09 21:20:37, Info CBS Session: 30817989_1489024411 initialized by client WindowsUpdateAgent, external staging directory: (null), external registry directory: (null
2020-06-09 21:20:37, Info CBS Appl: detect Parent, Package: Package_for_KB4561600~31bf3856ad364e35~amd64~~10.0.1.0, Parent: Microsoft-Windows-CoreCountrySpecificEdition~31bf3856ad364e35~amd64~~10.0.14393.0, Disposition = Detect, VersionComp: EQ, BuildComp: EQ, RevisionComp: EQ, Exist: present

Any ideas on how to solve this?

TIA!

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\PackageDetect] 

Its true that there are many entries in above registry key but depending on which feature you are trying to install,  you can limit your search down to very few keys. For example I had similar issue while installing AD Tools on RDS server. so i had to remove keys under "AD Administration and Tools". similarly when I was installing DNS tools I had to check few packages under DNS registry key. I succeeded at the end btw. Here is the procedure you can follow.

1. Open CBS log file  form c:\ windows\cbs folder.

2. Install the feature in Server Manager. it would fail.

3. Check error  logs and find out the package name which is causing problem.

4. Go into Registry, right click on the above mentioned key and select Find.. search the package i.e. "Package_1054_for_KBXXXXXX"

5. Delete package.

Repeat step 1 to 5 until installation succeed. 

some time you have to attempt installation too many time... To make above process more  faster, you can copy the  KB name i.e.  "KBXXXXXX" from the log and search it in very relevant key under "Package Detect".  Keep deleting these entries.. pleases note delete it under relevant folder like DNS if you are trying to install DNS servers or AD tools if you installing AD tools feature. Coz you are not attempting installation on every delete, this make this process much quicker. 

all the best.