I have the same issue and I am using the same mod as I have done through all versions of this VN. Broken saves appear to be a "feature" in recent releases of this VN. There have been quite a few times where I have had to start again and it is getting rather tedious!!If you used a mod on the last update, you have to use the same mod as you used then or the saves won't load. That's the downside using mods.
Also, I am not sure what the author is doing, but he seems to have lost direction in this story!
Kari turning into a slut even after the MC has committed to her!!
One of the girls being pregnant even though the MC never touched her!!
Maybe it is time to give up!