This is an edge case I’m sure, but was frustrating to me for a couple minutes. What I think happened is…
iOS Newsblur app was running in background mode. An already subscribed to site (http://getting2thehart.wordpress.com/) changed their feed so that it no longer has a title. Opened the iOS app, the feed was there with no title. I clicked the feed, and then clicked an unread post. On the single post page, since the feed was untitled, there was no text for the ‘back’ button to go back to the feed listing page. Since there was no back button… I was completely stuck on the single post page. Eventually realized I could force-quit the app.
On iOS app restart, the feed was renamed “[untitled]” and then worked correctly for story pages and the back button. Seems like if a blank title breaks an already running iOS app instance, you should check for and never allow a blank title - even while already running.