Verifying the Steam cache didn't initially turn up any issues. But when I manually deleted the "image.png" and "image_space_age.png" from the SteamApps directory and then re-ran the verification, it pulled those images down and now I appear to be able to start and run the game with no further issues.

Retesting on 2.0.21

Not only can I still not load the save in question, I appear to be unable to start a new game either

Tried to attach save zip to post, didn't seem to take. Trying now as a comment

Trying to load my save, haven't played in a week or so (I'm guessing prior to 2.0.20 patch).

Load progress stalls for a bit during consistency check, eventually kicking me back to the title screen with the error message

Error while running reload_script: copy_file "F:/SteamLibrary/steamapps ...