I know people have been having issues with their stats and ranks not saving and it resets a few levels upon logging in, but I haven't seen a topic about this yet.

Earlier I was playing when I completed the 200 kill challenge for the DSG. After the match, before I could spend the attachment upgrade my game crashed. Once I rebooted the game it showed that I still completed the challenge (showed like 204 kills or whatever) but I had no available upgrade to spend. I didn't lose any of my ranks, xp, or progress on any of my other modules.

Obviously this is a bug, and sorry if there's a topic about this specific problem, all the ones I saw were about people losing ranks.