@LoekDorMex I've merged your post with a longer thread for this issue. Please try the suggestions earlier in the thread. I'm not sure whether I mentioned it before, but if not, please also try disabling Windows Defender's Controlled Folder Access, that is if it's enabled currently.
@dawname Are you saying that moving the old save to the new Windows account caused the game to stop working in the new account? That is very strange, and even so, removing the save again should have fixed the problem. Since this is odd, I think it's worth running a virus scan. I'm not saying your computer definitely has a virus, only that it's a good idea to check whenever you notice unusual behavior that can't be easily explained.
If you want to try, download Malwarebytes (the free trial is fine) from here:
https://www.malwarebytes.com/mwb-download
Open it, click Scan > Custom Scan > Configure Scan, check all the boxes both for all scan types and for all your drives, and let it do its job. This could take anywhere from a few minutes to several hours, depending on the amount of data and whether the scan finds anything., so you may want to set it to run while you're doing something else. Please attach its report so I can take a look.