I think the problem may be with using the 'Back' option. This will take you back to the list of threads as it was when you last looked at it. It should not be updated with later posts.
Instead scroll to the top of the page & click either 'Refresh' or 'Lyrics & Knowledge'. Either of these will re-create the thread list for you, complete with any updates.
Using the back button & not seeing your own posts is one of the reason some people manage to post the same comment several times!