Masteries Please

I was in champ select for the last game I needed to rank into silver 1. I was deciding who to play top lane. I decided to pick Gnar, somebody I consider one of my more solid picks top. When I switched my mastery page over to his it told me that an error had occurred and to try later. I kept clicking on it and even onto other masteries. Then error kept popping up. Once champ select was over and the game was loading up I had no masteries on. None whatsoever. Of course playing against a pantheon laning was not fun. Now I don't think the game would have been much different if I had my masteries but laning would have been smoother for me. I just want this to be looked into and determine what the problem was. Thanks for whoever reads and can give feedback.