Xbox 360 games archivement dosnt unlock

I play Fable 2 on xbox series x and unlocked 10 archivements (or more) ingame the xbox 360 archivement unlocked pops out but on my profile and xbox app the archivements are still locked.

What bug is this?
I tought xbox backwards compatibility works 100 % fine and thats was the reason why i bought my first xbox in my entire Life to play Fable 2 and Fable 3.

How am i suppose to do 100 % when it dosnt work ??? (and yes i like it to collect archivements)

:)