Error Masteries

Having trouble selecting Mastery Pages. Every time I choose one it says "error, sorry about that we've sent a report to the server". I tried playing a few aram games to see if I could sort it myself but no matter which mastery page I select I load into games without one. Am I doing something wrong? I have tried closing and logging in mulitple times, no idea what I could have done to cause this.

ImperitorRex