Unfortunately, it has nothing to do with the char0-3 values. They worked fine before, even as far back as version 4. (2 years ago)
(And besides, the exps aren't saved in the char0-3. They're saved somewhere else)
I made an additional information in the post above to temporarily fix the issue, where it will change a small part of the save data.
But hopefully, you won't need to do this anymore in version 6.1.3.
Edit:
As mentioned by another person, the char0-3 may have indirectly contributed to this error, but not because of how big their save data is. I'll investigate this either way.
It's fixed, thank you very much :) My characters are back, even if at level 1. Some have 7 hours of playtime (as old as 4.0 over there), was more bummed about missing them than their exp, which can be farmed again. I reported in a previous comment days ago the "invisible" color missing from the palette, but now it's also working again as intended. Excited to try out the combo of news saying what the levels actually drop and the reduced prices in the boost shop.
On a unrelated note, may I ask you if you're planning to also add new clothes in the future?
Understood, thank you. Yes, some new designs would be great, would be something to look forward to unlock :) I have a smaller request, actually. Is it possible to add a zoom feature to the photo mode? It would be nice to be able to include the entire doll's body or parts of them in their picture without having to use weird angles.