Masteries gone

Today one of my friends logged onto League in hopes of playing Vayne, he is level seven with her but in the load in screen the mastery didn't show up. He hasn't played Vayne is a few months and is worried that he lost his masteries on all his champions he hasn't played in awhile. Is this a bug with Zoe coming out or is this a real deal for all the players who don't play all their mastery level seven and six champions?