Run FMGenieScout.exe as administrator.
Make sure to have FM21 open and a game loaded there.
Make sure to have your game saved before trying to load it in GS21g.
Close FM and re-open it, then try load game again
Thanks for documenting this. I'm having the same issue with Game Pass. I've tried updating the save file location (inserted \Gamepass) in Genie but it's still not recognizing the game.