Hello! I'm not sure what's causing this. There was a similar problem in the previous files of the game but it was fixed. Maybe check the game folder directory and deleted the .JSON files.
C: > Users> YourUsername >AppData >Local >nw-app >User Data >Default
Inside that folder might be three .JSON files, autosave, save and read. Delete them and see if that helps.
Sorry for the inconvenience!