I've got Game Pass Ultimate on PC, MS Flight Simulator is asking me to insert a disc.

First time I started it up I got the prompt for the disc. I closed it and closed the xbox app then reloaded the game. It worked the second time.

The problem for me was with the firewall (bitdefender).

Have to totally disabled it (since i wasn't able to make a rule for windows app .exe), then i was able to access game without disk message and continue installation.

If you can : make an exception rule on your firewall, if you can't' : disable it for the installation

Same here, except i have Standard Game Pass.

The store has pre-installed (before the official launch) 90Go (or so) from the 150Go initially announced, but after that he has never downloaded nor installed the 60 Go left, so i suspect this is the reason FS is still asking for the disc.

And i can't find anyway to verify it or manually update the game from the store or Xbox companion or anything else

I was able to play the game for a few hours this morning (via game pass for PC), stopped to update my graphics driver and now its asking for a disc.

If you’re inserting it, that tells me you bought the Windows disc version and live in Europe, or that you bought a copy of Flight Simulator X which is PC only. There is no Xbox disc release at this time.

No disc version of Flight Simulator will work on any Xbox

Flight Simulator 2020 only works on Series consoles, One consoles are not compatible