Hi all together,
I had the same problem after updating my emailadress for my windows account.
I found the solution, it’s quite easy.
Download x box companion app for windows. Ignore the information that new apps are available. Log out and log in again.
No problems with msfs 2020 anymore. Cloud sync works. Then updates.
I hope it helps.
Regards
Dirk
Edit:
I also tried the xbox app. Log out and in. This didn’t work. So I used the older xbox companion app which worked finally.