Yammer Files and Notes in Private Groups
Users are having problem accessing Files and Notes in Private groups. When users click on the Files or Notes links in a group header, the list of Files or notes that appears is unclickable. Files and Notes can still be accesses if clicked on in a conversation thread.
More information: Yammer Files and Notes in Private Groups
Story added 12. May 2016, content source with full text you can find at link above.