I have this same problem. Any subtitles added after the beginning of June 1st are not showing. (For example: For Here comes Jang Bo Ri episode 15 I see only ~33% of the subs.) The rest of the subs can be seen if I open the subtitle editor, but not when I view the episode normally.
This problem also occurs when I try to watch with ipad or my android phone. I've tried also different browsers and logging in/out, but nothing seems to work.
I have sent email to help. Hopefully this will get fixed soon, since watching via editor is not nice :/
(For some reason I can see the Turkish subtitles for Doctor Stranger ep 9, but not the English ones...)