and I as well am having the same problem. I've been investigating and testing.
the comment that was in the system, but not being displayed showed the comment author name etc, but no comment.
I copied and pasted it into notepad.
I began putting small pieces of it into the system and seeing where it stopped output. I'd do it line by line until it disappeared again.
I could NOT get past a certain point of characters and there were no "odd" characters in it.
the interesting thing is that the same comment author had longer comments above.
I then took the piece of the comment that would not show up / cause the problem, and posted it as myself. Then I edited it and changed the particulars back to the original comment author. In other words - he had two comments back to back so that it would display the entire comment.
these were comments number 18 and 19, so it's not as if it was a huge comment list or anything.
I'm about to see if it shows up again.
the comments in question are on this page, an interview with Craig Ballantyle
http://www.formerfatguyblog.com/interviews/turbulence-training-craig-ballantyne/#comment-1134
Comments #18 and #19