When a user is trying to login into their virtual desktop (RDS on Windows Server 2016) and is presented with an error message with the text 'We can't sign into your account" then follow these steps.
Look at the steps below to solve the issue:
Follow the message instructions and try signing out and back in
Look if the affected user is using an application that didn't terminate when the user logged out last. Some applications may cause locking user's session. Normally it's data syncing applications but could be other app that uses user's profile.
Check to see if the user is logging into a temporary profile.
Restart the session host server