Mine (either browser) shows no number when there are new posts -lol. After they are read i stays that way and if you re-access later and there were no new posts in the interim it will then show the number that WERE new (which you've already viewed), but if there were new posts in the interim it will, once again, show no number. So I sort of ignore it and just click "view all new posts" in the pull down which works fine.