I experienced the same thing yesterday, until I pressed refresh (F5) and then it was working completely fine. I saw it happen another time a couple of weeks ago.
This same bug was posted by a user a three weeks ago:
http://japaneseclass.jp/feeds/comment/4482
It seems that when it happens it might only be visible to that one user (not visible at the same time to everyone)? This bug might be adding extra stress on server if it's not fixed? Idk though.
June 3, 2014 at 5:47am