Please re-read the second post in this thread. It isn't designed to close that tag. It's designed to be used when you're *already inside a tag* to end it and start another one.
Like when you've quoted a post, you press-shift enter in the middle of it to close the existing tag, create a new opening tag after where you were, so you can reply to it in parts.
That said, it isn't working right now, though I figured that was due to my laptop having an odd keyboard.
Clearing the cache won't get you anywhere because the files are automatically compressed and they're given a new filename each time that's done so it shouldn't be caching anything because it's a physically different filename.