Computer is running fully updated KDE Neon Linux. Discover says firmware update is available.

Current Firmware version: 2.8.1

Most recent Firmware version: 2.21.0

Any attempts to update firmware results in the following lines at reboot:

Platform does not support this image

Failed to read header: unsupported

Failed to load image: Unsupported

start_image() returned Unsupported

Here is the output from running fwupdmgr security

Host Security ID: HSI:0! (v1.7.5)

HSI-1
✔ CSME manufacturing mode: Locked
✔ CSME override: Locked
✔ Intel DCI debugger: Disabled
✔ SPI BIOS region: Locked
✔ SPI lock: Enabled
✔ SPI write: Disabled
✔ TPM empty PCRs: Valid
✔ TPM v2.0: Found
✔ UEFI platform key: Valid
✘ CSME v0:11.8.50.3426: Invalid

HSI-2
✔ Intel BootGuard: Enabled
✔ Intel BootGuard ACM protected: Valid
✔ Intel BootGuard OTP fuse: Valid
✔ Intel BootGuard verified boot: Valid
✔ Intel DCI debugger: Locked
✔ TPM PCR0 reconstruction: Valid
✘ IOMMU: Not found

HSI-3
✔ Intel BootGuard error policy: Valid
✘ Intel CET Enabled: Not supported
✘ Pre-boot DMA protection: Disabled
✘ Suspend-to-idle: Disabled
✘ Suspend-to-ram: Enabled

HSI-4
✔ Intel SMAP: Enabled
✘ Encrypted RAM: Not supported

Runtime Suffix -!
✔ Linux kernel: Untainted
✔ Linux kernel lockdown: Enabled
✔ fwupd plugins: Untainted
✘ Linux swap: Unencrypted

This system has a low HSI security level.
» https://github.com/fwupd/fwupd/wiki/Low-host-security-level

This system has HSI runtime issues.
» https://github.com/fwupd/fwupd/wiki/Host-security-ID-runtime-issues