User blog comment:ThatRandomUser/TRU is in need of Help/@comment-5607198-20121217090845

Ok, the way it works is: you can only play a mission that you beat by loading the most recent save. If you turn on the game and LOAD as opposed to CONTINUE, and don't load the most recent save file, it seems to shut off the save. Furthermore, the stats CAN change, depending on the way you move from level to level, (doing them out of order fucks this up) and replaying a mission means you can't pull the achievement.