Making a call with CarPlay Spotify Continues to play.

[savante21]

When I make a call using CarPlay on a Kenwood DMX905S with spotify playing, the music continues to play low during the call.  Only I can hear it however and the person on the call cannot.

This does not occur if I'm listening to spotify as the source over bluetooth streaming, only during carplay use.

This also does not happen when I'm listening to other sources while carplay is in use, only spotify.

Any suggestions would be appreciated.  

I am a spotify premium subscriber with the latest iOS on an iPhone 8 plus and with the latest version of spotify.