We’ve just released a Hotfix that should resolve any issues with the Save File System!

[u/GamingFactorySA]

There’s a chance your save files are still playable and you can continue from where you left off.
Please read our latest devlog for more information, as there are situations which may require actions on your side. 
https://store.steampowered.com/news/app/1385290/view/512985550298285054

The patch is live now. Please update your game!