There is in an issue with the Master Chief Saga playlist on MCC resetting progress. Completed Halo CE and Halo 2, loaded Halo 3 saved and quitted it once initial cutscene ended and Sierra 117 started and the checkpoint had loaded. Gone back to play it again another day and it shows the Arrival picture on the load game screen, the game then loads up Pillar of Autumn and overwrote my progress.
Please fix this as I have to go back through the games. I love Halo and will do it, other players may not be so happy about it can’t say I was.