This question already has an answer here:
I've noticed this strange behavior lately. Whenever I comment on a question or answer, the
add/show 1 more comment link is displayed immediately, even when there aren't any new comments. When I click on the link, the message disappears, and no new comments are displayed. I have to reload the page to make sure there are no new comments on the thread.
I'm unable to reproduce the issue with a strict procedure and it doesn't happen all the time. So I believe this to be some kind of race-condition. I've seen this post on Meta and it's marked as status-completed but I'm still experiencing the issue.
I've also checked this answer and it says:
Localization is progressing, and the comments feature is on-deck, so I've been putting off spending any more time on comments until that's done. Putting this to status-deferred so I won't forget about it.
So, I'm wondering, what's the status on this?