I did all of halo ce on legendary but I didn’t get the achievement.Even though I did all of the missions on legendary I only have 50% on the achievement.And some I did two or three times and still didn’t get it. What do I do to fix that.
I had the same issue but with Halo 4. I found that by turning on scoring and beating the level in one sitting would make it unlock. Honestly I think the issue with the achievements stem from quitting and saving in a mission but I figured that having the game keep track of points would somehow convince it to realize that the level is finished when it tallies up my score.