new articles not shown in sources sidebar or dashboard

Recently (a few weeks back, on and off), feedly started to behave strangely with respect to new items: sometimes, for some feeds, when there's a new article in it, the feed isn't marked as having unread stuff in it in the dashboard. Nor is it shown in the "SOURCES" sidebar (I have it configured to show feeds with new articles only).

The new articles are shown in Google Reader, on the "what's new?" page on the feed's page (which I have configured to show unread only; yet, the new article is shown there.).

I know this is awfully vague, but I'm unable to find anything logic behind which articles are detected as new and which aren't. Restarting Firefox usually helps, but not for long. This is quite annoying, because the "what's new?" page doesn't show everything (and in my case, is frequently full of news I don't want to read at the moment), so I use the SOURCES sidebar as primary navigation tool.

In case the following description wasn't clear, let me show you an example: right now, there's a new article at Groklaw, titled "Stipulation to Lift Stay on IPO Class Action and SCO's MORs Filed". I can see it in Google Reader. On the "what's new" page, it is shown as usual in the "News" category I put this feed into. But on the very same screen, the sources sidebar does not list Groklaw, even though it clearly should, because otherwise an article from it wouldn't be on the "what's new?" page in the first place! So I go to dashboard and there's the Groklaw feed listed as having no unread items again. I click on it and feedly's Groklaw feed page is shown and has this new article in "today" section -- as a new one (there's "mark as read"). But it doesn't have the round box with unread articles count next to feed's title that is used to mark all of the feed as read.