If you stream audio over Bluetooth it will not show song data, doesn't matter if it's plugged into the USB or not.
If you plugin to the USB and press the talk button and say "USB" it will let you play audio using your standard music app, Sirius XM app, Pandora, etc. basically most things should play however only some apps will show the song data (depends on the app) like if you use the Sirius XM app (so it uses the Internet instead of satellite) it won't show the song data unless you use the MYSXM feature (at least from my testing)
Using USB also let's you use the voice commands to play certain songs, etc (ex: "Play Playlist Mustang", Play All, Shuffle, etc)
The car can get wacky sometimes like saying there is no USB connected when there is (unplug and try again) and sometimes will stop displaying song info all together
2013 V6 Black
"These cars are meant to be driven", so enjoy the hell out of all of it - not just the look of it when it is all clean" - Carroll Shelby