I suggest taking a look at your html sanitization settings make sure html isn't allowed in markdown settings.
Next step would be to move the other 2 topics from that category and check if you still see broken markup.
I am moving this to https://bbs.zzn.im/topic/3/new-site-setup-journal
I've also installed on Heroku but I'm having so problems... I've sent you a chat message
It's ok we chat here so other people can see it and maybe benefit from our experience.
@xinbenlv I think you can change this setting from Admin Control Panel... (or completely remove restriction)