Some users are able to log in and others are not, even users of the same OU. Example: OU "Test" has users tester1, tester2, tester3. tester1 and tester2 can log in with no issues and tester3 gets this error when trying to login. "The Group policy Client service failed the sign in. Access is denied.".
I have checked the registry and "gpsvc" and "GPSvcGroup" are correct. I have rebooted multiple times as well restarting the services.
It's a corruption in registry that causes the issue.