Cannot Change Masteries in Champ Select

I was just in the champion select screen for a ranked solo/duo queue lobby trying to change my masteries, which I do ever game according to the picks, but when i tried to save the changes from 18/12/0 to 12/18/0 I received a message saying "Mastery page could not be saved". Then, when I attempted to open the editor for my masteries page, it simply would not open. I was forced to pick an ADC mid lane because those were the only options I had as my keystone was warlord's bloodlust. I have not started another queue yet but I do believe this is a matter that should be looked into. Thank you!