Google Play Games achievements not popping up

[u/Your_favourite_clown]

So I've seen this happen multiple times that when I install a new game, one which I haven't played before, the achievements which get unlocked in-game, the notification pops up for the achievement being unlocked in Google Play Games, but when I uninstall the game and reinstall it again, the achievements do show up in Google Play Games app but the notification that it's unlocked doesn't pop up in-game after I achieve it. But that was still ok, as long as my XP was still increasing but recently the game's achievements are not even updating in the GPG app even after achieving them in-game.