I mentioned this in the actual devlog but old saves do not work at all. You would have to start over, but you can still utilize the skip functions. This is due to an updated renpy version that changed how I order my files, so things like... that happen, when you load old saves.

A reminder as well, new updates usually dont work with old saves regardless due to Renpy not being update friendly, especially since I often update the flow code every now and then. Please be reminded that this game is still in development so expect bugs when loading old saves even if they work.