Well f... This happened after the last hotfix.
What I tried to do and what didn't help to fix the problem:
1) Verified game files
2) Re-installed the game
3) Tried to change permission of C:\Users\user\Documents\Klei to "Read only -> no" (it didn't save for some reason) [1]
3.1) Oxygen Not Included's (Base game, no DLC owned) save files work perfectly fine despite being in the same folder (C:\Users\user\Documents\Klei\OxygenNotIncluded\cloud_save_files\*some_numbers*\*save_file_name*)
4) Launched as admin
[1]
My current settings. Repeating - ONI's saves work fine with them.
(Свойства -> Properties; Атрибуты: Только для чтения -> Attributes: Read only)
Has anyone else experienced this? If yes, how did you fix that?