thankfully the only thing that got wiped out for me is the melee kills i did the other day. i finished it and now i only have 30.. =( but i guess it could be worse. sorry to hear that.
i thought it was a glitch becuz i never played the story, so i finally did and when i finished it. i noticed my stats in extras only said 60 grenades breached, thats impossible. so i loaded co-op to see it said 0 on every challenge, then the server kicked me off and then i reloaded and all of my stats were back but the executions were back to 20/50. dammit... i was hoping theyd come back after playing a match, but nope..