[I just posted this as separate post, but repeating myself here hoping it will help you]
I have MS Store version. I was stuck with 1.18.15.0 and couldn’t find a way to trigger MS Store to download updates. The 3 part zendesk Download & Installation issues troubleshooter didn’t fix the issue. XBOX app removed mandatory update issue, but didn’t trigger updates. Finally I decided to uninstall MSFS. Luckily I stumbled on a fix:
Go to Add or Remove Programs
Select MSFS
Select Advanced Options
Select Repair
After the repair I switced to MS Store and it was already downloading the latest update (I have auto-updates on)!