The poster isnt able to explain themselves but Microsoft encrypts most of the game files for their gamepass games which prevents copy pasting the files elsewhere.
You can move the files but they are useless for any other version, and I believe you can’t even copy and paste from gamepass to gamepass either, but I can’t say for sure on that.
Well you aren’t going to be able to pick out a trend with only testing two games. Its enough of a problem that I would double check where the save is before starting a game on gamepass.
The last game I tried to move and failed was snowrunner I believe.