Okay, just wanted to clear things through here… I’ve finished the Campaign solo on Legendary - check my achievements. check my service record, check it all. but when i go through my campaign challenges it says i havent finished 2 missions? Excuse me? lol I’m pretty sure I would know it aside from dying well over 50+ just to pass through one mission lol. Trust me when I say I don’t want to do it again :)! I would greatly appreciate it if your could fix this 343i.
-Joeaccardo
I had the same problem. Is it that you don’t know what 2 levels or you just don’t want to play them again?
I had to replay the first 2 missions after beating the entire game on legendary. Sure I was a little miffed, but I went back and replayed them and just flew through the missions easy as hell. Every once in a while I’d remember it was on legendary and feel pretty good about myself. You feel like much more of a bad -Yoink- your second time through.
I have heard of this glitch come up a few times now - were you signed into Xbox LIVE while completing the progress of the campaign? Sometimes the commendations fail to “unlock” if you are not signed into Xbox LIVE.
Doesn’t resolve your issue, but I hope this helps.
It’s highly unlikely that 343i will give you the completion. You’ll just have to bite the bullet and replay the missions that it didn’t count.
I had this problem, it was because I didn’t do those two missions while I was online, so I did both of them again online and I got the commendations.
They were Infinity, and Reclaimer… You’re right I would have to bite the bullet the game’s screwed me more times than I can count, VERY aggrivated…
LUK30STEL0S99 thanks for the hint man, after checking my commodations i’ve noticed one mission uncompleted… sigh… this is going to take a while again ! 
I’m loving the subject title, lol.
But yeah, I have seen this happen to a few friends as well and it happened to me on my first playthru of Spops. Just replay the missions, it’s not a big deal.