1.If this problem occurred during RDS deployment, you could refer to RDMS log according to below KB for more clues.
Useful log files for troubleshooting RDS issues
2.Per searching, here is a useful thread where users shared their resolutions like:
- Manually add your Remote Desktop server into the MEMBER OF tab of “Windows Authorization Access Group” via Active Directory Users and Computers. (work for the situation that there is an old DC or upgraded one)
- Change the Windows Internal Database service to Log on as Network Service account.
- Open server manager - RD Services - Collections and create a new one (add your server to the collection)
It is worthy to test the mentioned resolutions discussed in the thread since a number of users have tested and resolved their problems.
Hope this helps and please help to accept as Answer if the response is useful.