Halo Reach making me buy again

Try deleting your profile and then resigning in. That should fix any licensing issues you may be having

i suggest trying a hard reset before doing what the ambassador above suggested, if the hard reset doesn't work then please do what has been suggested above.

I've encountered the same problem. One thing that has fixed it for me was going directly to the store and looking for the game there. Installing it from my games&apps didn't work but directly from the store did. Sadly I haven't had the same luck if the game
has been remastered, seems like they would rather you buy the new version.

Hope this helps!

Oh great! So all I have to do is go back to Game Pass and I don’t have to pay another 20$!

Ok, Thank you so much! This xbox community is actually super helpful snd I am very surprised that I was able to get replies overnight! Sorry about the threats to switch, I was just very angry and grumpy in the moment.