Thanks Greg. There does seem to be an issue with Digital ownership, it did show as "Install" rather than launch, but when I clicked Install it gave an error (Code: 0x80073CF9).
I originally played with Game Pass but then paid for Premium Deluxe. This worked fine but there was never any online server connection - I assumed it was a firewall configuration issue as I have a hardware firewall. However, when Game Pass expired nothing worked in spite of the in game screen where I purchased stating that all of MSFS was included.
I tried getting Microsoft support to sort it for weeks, but they refused to do anything but offer a refund of the upgrade price. In the end I agreed to a refund, but during the online refund process that was refused because it was 'beyond the refund period'. This was of course due to Premium Deluxe having worked all the time until my Game Pass subscription expired. After still not getting any resolution even after hours on the phone with Customer Service, I eventually asked my Credit Card company to cancel the original transaction which they were happy to do. Of course this still left me with no working version flight sim so I purchased Premium Deluxe and applied it to my account. This works OK, but there is still no multiplayer or online traffic servers connecting