Achievement not unlocked

Hello everybody.

Yesterday I played Halo 2 Anniversary with a friend and we finished it. But there is a problem, my friend unlocked the achievement “Legendary anniversary” (I don’t know if it’s correct, I translated from the french) but I don’t.

It’s the achievement that can be unlocked when you finish Halo 2 in the Legendary difficulty, and mine is locked to 69%. Another thing, my friend was the host during the game and each time we changed of mission, I always had the same loading screen, like if we never changed of mission, it may have something to do with it.

Is that bug known ?

Thanks in advance.

Yes it’s a known issue I believe that when in co op, heck even in single player, that servers may not register so you won’t get the achievement. These serer side achievements, especially in co op, are real buggy. Sometimes if you check your waypoint profile you can see what levels didn’t register as complete and you will have to replay them. Or sometimes if you are lucky it just takes time to register or a hard reset will register the achievement.

OK thanks for your answer. I will check on my Waypoint profile if I can see the levels that didn’t register.