I tried doing a backup and it says its completed right after u start but the back up is still going and I'm not sure if this is by design but while the backup is going u can still hit the back button. In my previous experiences u can't do anything until the backup is finished.
Edit: after a few reboots its working fine now.
Sent from my Galaxy Nexus using Tapatalk 2 Beta-6
Samsung Galaxy Nexus / HTC Amaze 4G/ T-Mobile Galaxy S II / HTC Sensation 4G / MyTouch 4G / T-Mobile G2 / Dell Streak / Samsung Captivate / Nexus One
/ T-Mobile G1