When the Vocera Edge app is open and running in the background, it interrupts the Apple CarPlay music player.
When the Vocera Edge app is running on your iPhone and connected to Apple CarPlay, the app’s background activity may cause CarPlay to prioritize it, leading to interruptions with other audio sources like your car's radio or XM radio. This happens because the app signals CarPlay to switch back to it, even when media playback is not active within the app.
As you’ve noted, closing the app restores normal functionality, which confirms that this is related to how the app interacts with CarPlay.
The customer would like to get this fixed.