When you will to "NPC reset" the message appears " Only level 30 or bellow can reset ". So i believe that.
In my case, when i finish master class i went to "NPC reset", but happens one error with the message "Level too high to reset skills", so with this message i can believe that
this message is wrong. Now I do not feel like playing, my build was a test, to when i come in level 30 with the masterclass i'd change.
It would be good to change the message! The dollar value is very high in my country to have a reset book.