For everyone experiencing issues with old saves. This is unfortunately due to how RenPy works. This happens most often when making changes to already existing files (so patch fixes are most likely to cause this) because RenPy is simply horrible at handling these conflicts.
This was the exact reason that Chapter Select was implemented, so I advise anyone experiencing issues to use that instead.
This is not exclusive to just this game. Even big games like
Summertime Saga have to deal with this sadly
View attachment 320043
I understand how this may be annoying to a lot of people. We will try to make as few of these conflicting patches as possible, but sometimes we simply have no choice.
In the future we will improve the Chapter Select so that you can use it in a more advance way, such as personalizing it to how your playthrough was originally.