Success … now my fresh FS2020 installation updated to WU3: UK. But why? What was the solution?
I don’t really know because I tried so much again and again and again.
The last thing I did before the update started to download was to logg off my Microsoft account from all possible apps (xbox, xbox life companion, ms store, edge browser, etc.). On the next FS2020 start the Xbox Login prompt appeared, I clicked on “Log in” and after that the update circle started turning and the FS2020 update window with the release notes appeared. After downloading 72GB I was able to access the marketplace again and download 4GB more of UK scnenery.
Hopefully this never happens again, I invested more than 12h in troubleshooting and re-installation tasks.
Happy Landings!