I have exactly the same problem: The button "Mark all as read" doesn't function when there are more than 50 unread articles. Additionally the text preview (displayed in grey) on uncollapsed items always states "undefined". Everything is working fine in Firefox. Already cleaned the complete cache of Chrome. Of course i'm running the latest version of Google Chrome, i. e. Version 24.0.1312.56 as of 30 January 201.