Hi there! That is strange, this is the first time I'm hearing about this specific bug. It might be because the older version you played was from quite a few updates ago. I usually only test save compatibility between the immediately previous version and the current one, so jumping multiple versions might have broken the stats. I'm sorry for the lost progress 🙁 I'll keep an eye out for this in future builds.
For this version, I would highly recommend just doing a fresh restart and replaying anyway. I have changed and added a lot to many of the girls' storylines since older versions, including adding voice acting, so a fresh playthrough will give you the best experience!