Lost ALL Progress (58% to 0%)

So… yeah. Playing some Halo. Finish up a game. Check my career stats, and it says I am 0% of the way done Halo: MCC. Seriously? Even my achievements (through the achievement app) show I have 7 out of 500 achievements, even though I was around 300 out 500. Does this happen to anyone else? I’m considering returning the game after this, and picking it up when everything is flattened out. Or should I say, IF everything gets flattened out. I had the usual problems with MCC, but I looked past them. But now that my progress and stats are down to 0, I’m finding it real hard to play the game again.