I can't get achievements anymore.

I can't  get any achievements anymore after I got the 'Archer' achievement even though I am in a survival world with cheats off and just the default behaivior and resource packs. It's annoying because my sister joined and she got the acheivements that I can't get, so I can't figure out whats going on. It wont work even when I switch accounts. It might have stopped working after I put on a resource pack and entered the world, but it doesn't change anything in the achievements, so I don't know why that would make them stop working.