I’ve been trying to complete the Campaign on Legendary difficulty, I have now completed 7/8 missions, but I’m missing Infinity… I was sure I completed 8/8 missions but didn’t unlock the Master Chief Armour, so I was confused. I saw Infinity missing so I tried the level again (from the start) and it didn’t work. It took me back to the home screen where I couldn’t do anything so I had to go back to Xbox Home. I’ve now tried Infinity 3 times and haven’t been successful in completing it.
Has this happened to anyone before? Or is there something I can do to fix this?
If you were not connected to xbox live when you were doing the mission then it won’t register the commendation for finishing the mission and that’s what get’s you the chief armour once you do all missions on legendary. So I’m afraid that you will have to do the mission again.
I was connected to xbox live because I was playing with someone on my on my friends for co-op campaign. Any other ideas? 
I’ll try doing the level on my own and see if that does it.
Nope!!! It hasn’t workee again!!! This is so annoying.
Chill, mate. The mods tend to frown upon double-posting, let alone quadruple. There’s an edit button for that, y’know.
First thing that comes to mind was the whole “Has to be on Xbox Live” issue, but according to you, that’s not the issue. I’d recommend loading up Waypoint maybe, see if there’s any way to check your progress there and see if Waypoint agrees with your console or not.
Otherwise, I recommend starting the level over completely, no “Continue Campaign,” “Rally Point Bravo/Charlie,” or whatever, just go from Mission Start. Then power through it, don’t save and quit or anything. I know Halo 3 always made it so you had to complete Campaign missions in a single playthrough for them to count. This isn’t true of Halo 4, but maybe doing that right now will help out the Commendation.
Try Solo, try Co-Op. I got mine Solo, I know people who got theirs Co-Op. I have no idea how fickle Halo 4 is, so there’s some chance that maybe it only works if you do it all Solo or all Co-Op, kinda like the LASO emblem?
Apart from that, there’s really not much more that can be said. Google it, see if other people ran into the same issue as you, what have you.
Thanks for your reply and sorry, I’m new to the forums.
I tried the “mission start” you suggested and I don’t see the option? When I try to select Infinity it only gives me the option to choose Alpha Bravo or Charlie. I’ve tried Alpha 3 times which is the start but it didn’t work.
I’ll have a look into Waypoint.
EDIT
I found another post the other day on here about it and it was given the response to start the mission from the start, but it was no use to me as I have done that.
Here’s the link if you want to check it out:
https://forums.halowaypoint.com/yaf_postsm1795284_Campaign-Error--Infinity-Glitch.aspx
> I’ll have a look into Waypoint.
I’ve had a look at my waypoint and it also says that I haven’t completed Infinity on Legendary, which I have…
I completed it SOLO ONLY while i was connected to Xbox Live and it worked.
I’ve also done that, but when I complete the mission, it takes me back to the main screen after a couple of minutes of a black screen with the white numbers in the bottom right hand corner.