Stories for some sites are fetched correctly but never shows up as unread

For example: “Planet Clojure”. Some details in this feed:

* It has currently 163 subscribers in NewsBlur
* For me the feed is updated every 10 to 12.5 minutes
* It’s updated fairly regularly with several new entries every day on average

And in fact if I manually go to that feed I see all the updated stories but they are always marked as “read” and I don’t see them if I filter my feeds for unread items. I’ve noticed this problem with the regular UI, tried and the problem seemed solved (at least for that particular feed). However since maybe the last 2-3 days, that feed is again always marked as read (both on stable and dev).

Sadly this defeat the purpose of an RSS reader if I can’t trust it for showing me all unread stories for the feeds that I’m interested in.