had a fully working version which asked me to update, and then after the update i was not able to connect to my watch !! Garmin tut-tut i then tried a re-install of my device and software to no avail.
quick fix for me was:
1: delete it from your windows but uncheck the delete all files box to keep your info.
2: download older version from here https://garmin-express.en.uptodown.com/windows/versions , i used 18.104.22.168
3: disconnect pc from web and install the older version, start Garmin express, it will say web not available just ignore for now, click on your device and it should load up, if your device doesn't show then re-add it and open it up.
4: now with express still open on your device re-connect back to the web, it should ask you to log back into your account, if not then log back in.
5: update to the latest version, it was 22.214.171.124 for me at the time and all now should be good, hopefully, Garmin will sort the update issue until then i hope this helps all that it's affected.