Issue with Navigation/Music while on bluetooth

Dec 7, 2016
I drive part time for Uber, and have just had a problem pop up this week with my NAV apps. It doesn't matter which app I'm using (Google Mapps, Waze, or the stock iPhone Maps), the following happens.

In the past, when a new turn-by-turn instruction would air, the music (or podcasts) volume would lower and the NAV app would speak over it. Just yesterday, it started pausing the music instead of just lowering the volume. The problem with this is that it also pauses (or mutes) the turn-by-turn as well.

Is there a setting that I have somehow changed that would allow the turn-by-turn to speak without muting my music?