Mastery Page Error

Alright, so I tried resetting a mastery page recently and a message popped up saying there was an error. It was not descriptive or anything, just stating there was an error. Now, I can not create or modify and pre--existing pages and i have no control over which mastery page is chosen when i go into champion select. I tried repairing the game, but that did not work.

UPDATE: After reinstalling the game, it turns out the error only appears when I try to name a mastery page: "AAtrox". Nothing else procs the error it seems.