Hi,
I tried upgrade MSSQL and PHP to latest version with no result.
Also I added a new MS App to test.
Still the same behavior.
It realy seems to be the Redirect-URL which makes troubles suddenly.
"http://localhost/osTicket/api/auth/oauth2" -> MS Authentication works (verified in Azure) -> Back to osTicket and it gets me to "http://localhost/osticket/"