I have completed every mission on at least heroic but have not received any of the Xbox campaign achievements. It looks like two missions did not register and I am wondering which two they are. I have checked every game (Halo 1, 2, 3, 4 and each one says I completed each campaign on co-op. If you could look up which missions did not register I can redo them.
Your service record on here shows Uprising is missing in Halo 2. Other than that, you may want to go through and complete all the missions solo on a lower difficulty and see if that helps. I’ve heard about some difficulty achievements getting stuck if you don’t have the missions completed solo.