Halo 4 Campaign Co-Op problem

So me and my friend and his guest decided to go and do the Campaign on legendary. We finished the entire thing soon enough but there is a complication. It seems I didn’t get it for the level Midnight. Why not? I noticed and we redid the level Midnight and still, when I look at the campaign level selection, the Co-Op section is blank as if I never played it. Why?

This one level is denying me a few achievements and the Mark VI armor! For some reason, he got it no problem, but why am I being denied it?

same thing here… let me know what you find out!!

You got the same problem?!