[CLIENT] Alpha Client Bug: Mastery Page Window

Massively inconvenient bug in the current alpha client; mastery pages get stuck on the screen during champ select. The mastery page window works as normal, but pressing "X" doesn't close it, meaning the player can't change summoner spells, rune pages, or LOCK IN. This has happened to me a couple times, both leading to me incurring the queue dodging penalty.