I saw you said you played with “User Assignments”. There are 2 things you may want to review.
1) The policy “Log on locally” should have the default “administrators, backup operators, power users, users, Guest”
2) The policy “Deny logon through Terminal Services” should not have any users listed or default which is “None”.
I am sure you must have checked, but you didn’t actually say. Did you go into the my computer properties and make sure Remote Desktop is enabled on the client?
Yes both 1&2 above have been done. Have also checked RDP is enabled on all PCs
Run RSOP on a workstation and check GPO Settings. See which policies are winning. then check them to see if something is set incorrectly.