Mastery Page Bug

So, from my understanding. this bug has been around for awhile. But if you open your Mastery Page in Champion Select, edit it, and hit space bar two times. It'll freeze your mastery page so you cant even select a champion, or anything. The only way to fix this is with a client restart. How do I know this? Somone just told my duo partner this, and froze his client, making him dodge.