Item Sets have Disappeared

So I was messing around with my item sets while waiting for a team builder match. I skipped the lobby it just gave me and went back to my profile, and as usual it displays the message "Do you want to save what you had done?"

I clicked "Cancel" because I never try to save incomplete item sets before I go into a match. I go back to my item sets... and they're all gone. Ever last one of them. It even gave me the custom item set #1, so there were literally none on record and they weren't hidden or anything.

This really sucks, I know I probably won't be able to recover them, but here I am letting others and Riot know, so... I wasn't the only person affected by this either, I've asked around while in game, and at least one confirmed to me that they have the same problem.