I noticed recently that the "view more comments" link failed to work rather often for me, usually on pages that I had opened earlier and that were open for some time. I suspect that it happens only if more comments are added after the page was loaded, but I can't be entirely sure about it. It also does not seem to happen for every case where comments are added via the live update, only if the page has been loaded for a while.
The comment link just doesn't do anything at all in these cases, I inspected the page and it looks to me as if the event listener that should be triggered is just missing entirely on the "add comment" div.
There is also one similar bug report on meta.physics.