I've noticed at least once, that a reply I made to a post doesn't show (at least for me) on the main post page, although it is accessible for both me and the OP at the direct link. But once I collapse the conversation, I can no longer see my comment.
(I had to refresh three times through no-authorisation to find that direct link, BTW. Hmmph.)
AND CLEARLY I'VE BEEN BEING MY MOST BRILLIANT EACH OF THESE TIMES.
That goes without saying.