A few mutual friends and I realized that some games don't appear in our Xbox App (mobile) library.
Just to clarify, these same games can be played on the Xbox, and appears on the console (library/purchased), but some are not visible on the app (mobile). One of these games that we have in common is Resident Evil 7, which does not appear in our library (Xbox App mobile).
I tried several times to speak to Xbox support a few months ago but without success. I don't know if anyone else had this problem. It's not exactly bad since the game is accessible on the console, but I would like to have everything organized and visible in the app.