For the people that don't know how to use these codes, just log into halo waypoint, and then go to the classified section to enter the codes. You can also do this from waypoint on the 360 apparently, but I've never done it from there.
its happened to me i am back to sr1 and cant level up or use loadouts
well, poop... This SR1 glitch has been happening a lot lately. Just need to sit and wait for 343 to come up with a fix I guess. I HAAAAAAAD to use an XP only code when I was already max rank... Hopefully it'll be a quick fix.