Ran into this today. Playing audio on my 2012 Lexus CT200h over Bluetooth using my iPhone 4S. Audio would play for about 3 seconds, then show paused, about three seconds later, I'd hear the iPhone playing the content for about a second, then it would start the cycle over again. Tried turn off/on bluetooth on my phone, turning the car radio off/on, reselecting my phone from the bluetooth audio setup menu, rebooting the phone, rebooting the car (at a traffic light, I switched the car off and back on again). No dice. The solution that I needed to select phone (not just audio player).
[Talk] Setup [Talk] Phone Setup [Talk] Select Phone [Talk] <phone-name> [Talk] Confirm
BTW: Bluetooth Audio is nice, but I'd be happy if the USB interface worked better. USB prevents the phone from selecting or viewing the music selection from the music player app. Yes, I can use the car's interface, but that is epic fail town.