SO. I need some testing.
People having this error...
Did you accept any compensation AP on that character back in the day, when they were handed? Since it affects mainly mains, it most likely has a relation.
I need to collect enough data to know this, and then let Nexon know.
EDIT: used the scroll to set the 10 extra AP to hp. No changes. Dammit. Still, report in in case that's the relation.