I was level 46 and we were taking a break. Backed out of the lobby and left the room. Came back to a message about being logged off because of inactivity. When I signed back in, I was level 1. Tried everything I could think of (reseting the game, hard restarting my xbox, starting and backing out of a game). I have 16 hours of gameplay into this game. I don't think I'd have the heart to go for "Early adopter" achievement if there's the possibility this might happen again.
Platform: Xbox One
Gamertag: DarkGhost08
Your Country: USA
Data Center connecting to in game: East US
Have you purchased the Season Pass: No