Okay, so I got on my Xbox on my other account, which has been a 130 for months. And all my stats are here, but it reset my armor, loadouts, stances, service tag, etc. So now it says I have 35 new loadout items, 280 new armor items, and 117 new emblem and stance things, when before I had 0 new anything. Also, it showed the “Welcome to War Games” humanity cutscene before I played. I’m not mad at all, I just want to know why this happened, maybe it’s a bug that 343 can fix or something. Any insight would be nice. Thanks! God Bless you 
yep… Happened to me 4 times already. Your campaign progress resets also.