Welcome to the forum, @Jelamah 
Actually, this was reported long ago and there’s a lengthy discussion about it, but devs had always problems to reproduce the issue.
If you go to the savegame folders, do they have 4 files each? Is there any folder that is empty?
There was an old workaround for when the game is not saving if you want to try it: either delete all your saves (it’s probably that one of them is corrupt) or place them in another folder and try leaving only one of them in the folder, and see if it loads and saves again correctly.
But this might not have to do with this bug, since it happened to many people in the past. Seems that the save/load problems are returning. 
Thanks for reporting! Any tips for reproducing the bug would be great.