In the Android app, if I’m reading an article and Newsblur updates a feed and caches a new article while I’m reading, hitting “back” to go to the articles list will show the article I was reading as unread (and other more complicated versions of same). This seems blatantly to be some kind of synchronisation fail, where the underlying sequence-of-articles list has changed, but the corresponding sequence-of-read/unread-markers isn’t updated accordingly.
This has been a problem since I started using NewsBlur a couple of years ago; my search-fu seems inadequate to finding others’ descriptions of the problem though. I’m sure this must have been discussed to death?