Champions missing from Champion Select BUG?

Whether it's free-to-play champions or ones I don't own yet, none of them show up as an option. A few days ago, everything was working pretty fine and nothing was missing from my champion select, so I was playing a lot of FTP Sejuani. That was until I logged on and took her into sandbox mode. And after that, she just hasn't been showing up at all. And I noticed that other champions I don't own haven't shown up as an option. From what I remember if you couldn't select them, it would just be a gray box icon instead of completely missing. Is there any solution to this?

Edit: I've tried initiating full repairs but it doesn't seem to do anything.