+1 Same here, savegame get corrupted every time i close and re-open the game.

Also tested with Lutris+Wine Staging and windows 7 and the problem is only present on Proton.
EDIT: Problem is on Steam Clound sync, disable it for this game to avoid corruption.
This seemed to trigger for me with cloud sync, as well, but it would do it when switching between Windows and Linux. It's possible it might only trigger if you have it installed on both platforms, and perhaps if you have both OSes running at once on separate systems that would cause it to instantly corrupt the moment you exit the game?
same here, if I put steam in offline mode (or unplug the cable) the corruption doesnt trigger, whereas it triggers right after steam "syncs" the game.
I played the game on windows 2 years ago, and I have two saves.
thx
This is fixed in the current Steam Client Beta:
https://steamcommunity.com/groups/SteamClientBeta#announcements/detail/1691556695813620029
proton 3.7-4x1 2018-08
This happens randomly when I quit and reopen the game then I come back to my save file stating that I'm in dev mode and that my file is corrupted. I can't continue playing my save file after this.
I'm using Proton 3.7-4 Beta.
System Information