Hi
This thread with similar issue might be helpful:
https://social.technet.microsoft.com/Forums/en-US/58d44320-9551-404a-9616-278f5457f815/windows-server-2019-black-screen-for-default-administrator-but-not-other-enterprise-admin?forum=ws2019
I hope this information above can help you.
Please feel free to let us know if you need further assistance.