Hi @Joel Newton
Thanks for posting your question in the Microsoft Q&A forum!
The error message is "DeletingCloudOnlyObjectNotAllowed." occur when an object was converted from a synced user to a cloud-only user, however, the user may not have been deleted properly from the on-prem AD or it caused by the account being restored after being deleted by the Azure AD Connect service, before it could confirm the account was deleted.
When you try to locate the user by the ID in PowerShell you are unable to find the user. may I know what the PowerShell is command you have user?
If you are unable to find the user you can identify the user via the Azure AD Synchronization Service Manager under the Metaverse Search for more information please read Sync Service Manager Metaverse Search
Also, you can find from Entra ID portal under users by using the attributes like email or name or other profile information associated with it.
Reference: https://learn.microsoft.com/en-us/answers/questions/905372/deletingcloudonlyobjectnotallowed
Hope this helps. Do let us know if you any further queries.
Thanks,
Akhilesh.
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