I have ccompleted halo 2 on legendary but I haven’t managed to get the achievements for it. I’ve looked back to see if any missions are not complete, every level has the legendary picture on it :s
Me too…
My achievements for the whole Halo 2 Legendary done on campaign did not unlock at all (same for Heroic).
But the game itself says I finished the game on “Normal”, although in the mission selection screen, every missions have the Legendary logo.
I’m having the same issue with Halo 4. It’s definitely extremely frustrating, and from what I’ve heard, there isn’t really a solution.