So there it is....my first and ever problem with MSFS since it's launch <- yes, this is correct!
Last days I got plenty of "unable to sync" messages and it was always the XBOX Gaming App that logged me out. Looking in the Store Updates I saw the last days constant updates to the XBox gaming app and the Gaming services (just today again).
So now I have my first stuck on Checking for updates screen. Nothing helps....
Anybody else having this?