Same problem!
I am Magic Gladiator 400lvl 46 resets, try to gain master levels in Karutan, nothing, about 10 minutes and nothing, my nickname: Alester
P.S. After aboout 30 minutes fighting i Karutan i didnt get any levelup, its telling "You are reached a maximum level" and thats all, and a bit fight in Kanturu Relics, nothing