I just experienced this, wouldn’t let me save manually. When I went back to the game to load my saved game, the game now crashes. I have lost a total of about 45 hours of building etc.
I know its “early access” but man this hurts my soul.
I tried older saves etc etc, nothing works now. Constant crashing tot he point I have to hard reset my Xbox.
By the way, if devs read this, I LOVE your game. I am playing on an Xbox One X, Single Player Creative. (This is what I was doing today).
Otherwise I usually play with two others in multiplayer, I am the host (Xbox One X), one of the guys is on One S and the other guy is on a basic One - our save game is also lost/corrupt/gone.