Tested browsers: Firefox ESR 45.4.0, Pale Moon 26.5.0, IE11
When you try to post a comment in Coffee Corner with viewability setting other than Viewable by all users, the Submit functionality does not work. On a second attempt, the Submit button becomes inactive and you remain on the same page with the not submitted reply.
A moderator confirmed that the reply was not submitted.
Can you please check if this is browser-dependent or it is related to the user not being a moderator? The functionality seems to work for moderator users.