Please keep in mind, the sound settings of each app are set by the needs of the app and cannot be altered. So, if you are playing a game or using an app that requires sound, the audio from Pandora may pause. It's not possible for us to override the sound settings, or any other functions of another app.
Are you receiving any error messages when this happens?
In the meantime, did you have a chance to try out these steps to see if it resolves the issue you're experiencing?