achievement done but stuck in unlocking

I have the Pillar of Autumn achievement done some days ago but the UI says unlocking… What does it mean? What should I do?

I have the same problem with halo ce final level and the first three levels of halo 2. along with some medal based achievments

Same issue with Cairo Station and Outskirts achievements; you can look at my campaign progress and see that I have beat those two missions.

The only thing you can do is wait. It will unlock eventually. Perhaps after the update.

I hope so. I got 6 achievements still unlocking since a week ago…