Huh, this is weird. So some of us are having this issue, while others are currently in the game?? No idea what's happening here my friend.
Downgrading is not possible since you cannot select a specific game version. If you go to Steam>ATS Properties>Betas, you can select the third option down, but that is only 1.0.0.4, which is too old.
So neither upgrading or downgrading works, yet others are currently playing?