Achievments not unlocking. H5 and MCC

Long story short, I’ve completed all the MCC campaigns on solo legendary, as well as H5. Yet in both cases, the games are not giving me these achievments yet they show all my missions solo legendary complete in the menus. I’m tired of this crap and want it fixed, but there seems to be no way to contact 343. Help?

There is a glitch on MCC, which will not give you credit for a mission, if you saved your progress and came back to finish it. So in order to get credit, you have to complete the mission from end to end. Looking at your record on H2, it shows that 3 missions, Metropolis, Gravemind, and The Great Journey, are not completed. This was because of the glitch. I had to go back and re do some missions in order to get Helioskrill. You can check the missing missions here on waypoint.
I do not know what the issue with H5 is. I completed it solo, and received the appropriate commendations.