First, thank you Denton for letting us know about your issue and the diagnostic that worked to resolve the issue.
Second, Elbe, from what I can see in the output_log.txt file, it seems your game is having trouble finding some files. The first thing I would do is temporarily remove the mods that the report says you have been using to make sure that they aren't causing any issues after the most recent patch update that we released. If the issue persists, then I would have you repair your game files via GOG to make sure they are all present and accounted for. I'll list instructions on how to do this below.
1. Launch GOG Galaxy and log in with your GOG.com account.
2. Go to the game's tab.
3. Click MORE > Manage installation > Verify / Repair > VERIFY GAME.
If verifying the files didn't work, then I'd try uninstalling and reinstalling to force all files to go to a specific place where the game should recognize since they'll be freshly installed. In the event that doesn't work either, please let me know so I can have the team look into the issue further.
We are still on break until January 2nd, so I'm hoping this can get you going sooner. If you do end up needing further help, would you also be able to provide us with a save file that does work and a save file that does not work for the team to use for an investigation? If needed, you can find instructions on where the saves are located here. If the files are too large to attach to the forums, please send them to me at firstname.lastname@example.org along with your user name and a link to this thread as a reference.
Thank you everyone, and sorry for the inconveniences you have been going through.