items not staying as "mark as read"

When I access Feedly and mark an item read, either by auto-marking it by scrolling down the page or by clicking the "mark as read" button, they appeared marked as read. However, a few seconds later the items unmark themselves. It doesn't matter what layout I am looking at (home, latest, or specific category) this always happens. When I check Google Reader by itself, the item is also unmarked there. However, when I mark an item read on Google Reader, the item stays marked.

I am using Firefox 3.5.2 running on Mac OSX 10.5.7.