I'm a Teleporter. My maximum CP is currently 21500 (9,500.0+12000.0) and my maximum Overload is 1,100 (600.0+500.0). My skills are currently at 100% on everything, except for Brain Course Advanced, which is stuck at 36.1%, and Mind Course, which is stuck at 0.0%. No matter which skill I use, they won't improve.

It seems the completion level for Brain Course Advanced and Mind Course don't go up when you use skills you've already 100%ed. I'd assume the same bug effects Brain Course, too, though I already 100%ed it before hitting this bug, so I can't be sure.