Lone Wolf Achievement Won't Unlock

So at around 7:25 p.m. central, I beat the Halo 4 Legendary Playlist and I played it solo for the “Lone Wolf” achievement and after beating Midnight, I unlocked four of the campaign difficulty achievements, except for the one titled “Lone Wolf”. I even have proof that each missions says it’s been completed on solo legendary, but no achievement. Could someone please give their insight on this issue?

This might sound stupid, but did you complete it in order