I have set up a WVD hostpool with a Windows Server AD using Azure ad Connect. There is a problem with one user getting an error when trying to start the Remote Desktop, it works fine logging in to rdweb.wvd.microsoft.com/webclient/ and there the user can see the Remote Desktop but he is getting an error when he starts it. I have tested created a new user account and that works fine. The assignment to the Desktop group is done the same way for both users using powershell.
This is the result when running Detailed Diagnostics for that specific user.
ErrorSource : RDBroker ErrorOperation : AuthorizeUser ErrorCode : -2146233088 ErrorCodeSymbolic : ConnectionFailedUserNotAuthorized ErrorMessage : User ≤firstname.lastname@example.org≥ is not authorized to access the resource ≤mth://localhost/8aaea36-ad40-49cb-a6b7-ba7d9690d1a8 ErrorInternal : False ReportedBy : RDGateway