For what it's worth, I don't think we've ever the disk information screen working on the Dashboard, with the error "Failed to connect to Default Member".
If this is the case for you, it might be worth looking down installing a different Kernal route, as we've had mounting problems on newer hardware in the past. (UEFI caused various issues here)
http://community.spiceworks.com/how_to/show/1951-change-the-kernel-that-fog-clients-use-for-pxe-boot