I did the software update on my 2013 X3. I run the app in the background, run Spotify, select the source to be the phone and voila, I get sound through the USB connection.
However, the communication test fails and most functionality through I drive is lost. I have looked all over the Internet and many people have that issue. It seems like this is an app problem. I hope BMW fixes this issue at some point.
Fe-li-pe about BMW Connected Classic