I have been trying to get all the achievements in Halo: MCC on PC as the games come out but I have also already played before on Xbox. I have beat every game except for halo 3 ODST on legendary and it says I still have four levels left. I beat Halo: CEA last night and the game refuses to say I completed the last four levels on any difficulty I replay them on. The levels Waypoint says to replay are: the library, two betrayals, keys, and the maw. I don’t know what to do as these levels took me the longest.