Error while adding host access to a datastore

ESXi model PowerEdge r640 version 7.0 update 3

Unity 350F OS version 5.1.2.0

I recently had to remove ESXi host access from a datastore, then add that access back again. Every time I remove or add access, the unity GUI returns an error message that reads "Adding host access to the datastore partially failed (Error Code:0x5c00106)" despite this access was removed and then added again seemingly without a problem for three of the datastores I did this with. But two of them refuse to be read by the ESXi host for some reason. One of them when being added again reads "Manage host file system using block... failed" now as well. That one doesn't even show up in the ESXi's "Storage" section. The other one not being read does show there, but its capacity says 0B and none of the VMs that run off of it are able to function.

I guess I'll post this again under the ESXi forum but in case it is a unity problem I'm leaving this here. That said I get the feeling it's not because both of those datastores can be added to the other ESXi host that Unity system is connected without a problem.