Challenge numbers frozen glitch

Hi there, for a few of my challenges, the numbers were previously increasing normally but now have frozen, and don’t increase no matter what I do. So, in other words, the game previously registered that I was playing Halo 3 matches, but now no longer registers when I complete one. The same for vehicle-related kills, or covenant weapons, or… well, you get the idea.

I’ve tried restarting the game, logging out and back in, restarting the xbox, etc. – nothing seems to work. Anyone else have the same problem, or know how to fix it?