Can you try a rebuild and restart?
Edit: Cleared cache and it's fine
Yeah, I know...
Turns out certain things don't work in IE11.
The expanding button in the bottom right doesn't display either.
So sick of IE and its isolated problems. (╯°□°）╯︵ ┻━┻
@trevor Funnily enough, I read an AMA on Reddit with a couple of the devs, and decided to try it. First site I visited.
Good job IE. Maybe next you can implement WebM support as standard without needing a Codec from Google.