Achievement Progress constantly resetting

Why is that the only time I have achievement progress reset is with this game or it’s not even tracked properly? I was 2 damn grenade kills away from having the achievement done and now it got brought down to 112 out of 500. WTF is going on with this game? My legendary medals achievement isn’t even tracking right. I’m only 24/7 so syncing shouldn’t be an issue like it is.