I finished mission 2 on Legendary earlier tonight and sadly no achievement popped; so I check my list and I noticed I got no progress for it on any of the Finish Campaign on Insert Difficulty Here achievements.
Now I had this happen before on the MCC, and I checked my records on here to see which didn’t register; however this time I checked on here thinking it would be the same issue, but it even acknowledges on this website that I completed the level on legendary??? So why didn’t I get the achievement?
Anyone know?
Same thing for me. I have no achievements for completeing Levels 14-15, and any for Beating the campaing on Legendary… Pretty dissapointed right now.
I also went back to my endgame checkpoint and finished it again, this time when I got back to the main menu, it said “Profile Sync Error” Error writing to Halo 5 Profile, Please try again later.
Hopefully that just means it’s delayed, otherwise I’m going to be pissed if I have to do those last two missions solo again.
Also, worth mentioning it is recorded in my Service Record I’ve completed the missions 
very similar issues. check my service record…only 2+ hours of play and solo-legendary completed. received all my proper achievements just on my service record it only shows details for 2 levels for some reason (add in the other levels that aren’t accounted for and i guarantee that number goes up).
Some people say hard reset your system works
Just checked my Xbox today and apparently the Achievement is unlocked now and the appropriate progress to the other campaign achieves has been applied. Odd, but still happy that it worked out