My replies disappear from threads

There is problem where when a thread has more than a few replies many of the replies will disappear. It does not matter how many "load next" and "load previous" buttons I click the missing replies just do not show up.

Sometimes I can find my replies by going to my activity and looking for a particular reply and selecting it.  But I doubt the same is true for the individual I am working with.  Likely they have no visibility to the reply.

What's wrong the the system?