I just beat the game on solo legendary and I did not unlock the mark IV armor. Please help me unlock the armor! I only beat it on legendary just to unlock the armor 
thanks if you can help 
Well assuming you completed the Campaign online, you need to check your Campaign Commendations and see which mission(s) you need to complete again.
I’m about finished the campeign on legendary and noticed that i skipped past the opening cut scene. It says i only did Dawn on Normal. this may be the problem you have. Go back and watch it and the armour and achievment may appear.
I checked it and its says I have completed all the levels in solo legendary. No idea what to do now hopefully the developers check Into it, I want the mark IV so bad! Lol
Never mind! I was offline when I completed the two of the missions… ://// thanks for your help !!!