Windows Server 2019: Can't add locations to index for windows search

i'm obviously far too stupid, but maybe someone has mercy ;-)

System: Windows Server 2019 Standard DC

Tested Users: administrator

Problem: Windows search Server index only includes one useless location: Internet Explorer History. As a result there are 0 indexed files Screenshot.

And i can't add any other location in indexing oprions -> more, because the show all locations button is greyed out screenshot.

What have i have tried so far:

Windows index service troubleshooter
Rebuild index
Move Index to different folder
Uninstall / Reinstall Windows Search feature
Try with new administrative user
and a lot more..

ANY SUGGESTIONS APPRECIATED.....

Thanks a lot !