Curious bug then! Thank you very much for enabling me to continue playing

Only older copy of this save file in my backup is from 4 days ago. Attaching it to this post.

It loads for me with no problems.

Annoyingly, no I don't. I (perhaps foolishly) always saved to the same file. None of the 3 autosaves are loadable either.

I'll try tonight to see if I can get an older copy of the save file from my backups.

Attaching log file.

I cannot load my save file (attached), I get the error message: "Internal error, unknown tile 23".

No mods are installed or have been used during this playthrough.