[Laineyc]

I have this enabled in the Google Maps settings. Instead of sounding thru Bluetooth it can't be heard at all.

[mrpackerguy]

This is a common issue. Same with me. It works when you use the Bluetooth source rather than leaving it on radio or other source. I just turn up phone volume

[GSDer]

@OP,
You didn't mention if you're on the stock Android 9 (Pie) build or the Android Q Beta 2 build.
I've had this happen on the latter, even though phone calls still come through on Bluetooth. Usual solution is to restart the phone.

[foxbat121]

This is a common issue. Same with me. It works when you use the Bluetooth source rather than leaving it on radio or other source. I just turn up phone volume

There are two separate Bluetooth protocols involved: one for phone calls, one for music/other generic audio. Maps and other apps only use BT music audio protocol which requires your radio to use the specific BT source, not the phone call protocol which auto switch to when ever there is a phone call but with much limited audio quality.

[Laineyc]

Yeah, I have no problems with Audible books or any of my music apps. I thought I'd be able to hear directions through the radio speakers even while I had Sirius radio playing. you know - have it interrupt the music. If I have to keep the radio on Bluetooth to hear the directions...a lot of empty air.

[Mike Dee]

I assume your vehicle doesn't support Android Auto

[foxbat121]

Yeah, I have no problems with Audible books or any of my music apps. I thought I'd be able to hear directions through the radio speakers even while I had Sirius radio playing. you know - have it interrupt the music. If I have to keep the radio on Bluetooth to hear the directions...a lot of empty air.

Google Maps or any other nav software never able to do that. I have a car that only support phone calls, not BT audio. In the old days, there are apps that allow you to route BT audio to BT phone protocols but those have long stopped working.

For clarifications:
1. BT audio uses A2DP protocol and requires your BT device to switch to BT audio source. It supports high quality stereo audio. No MIC support.
2. BT phone calls use BT Hands free protocol that does not require audio source switch but it is only meant to be used with phone calls only. It only supports very low quality mono audio output and MIC support for pick up your voice.

Apps mostly only use #1 for BT audio output unless it needs the phone call functions. Only phone dialers use #2 . At Android OS level, it seems to enforce that separation in modern versions.

Android Auto is the future.

[Laineyc]

Android 9

[Laineyc]

Correct. 2014 Acura TL

[GSDer]

If I have to keep the radio on Bluetooth to hear the directions...a lot of empty air.

Yep, that's what's required.
You should be able to stream a podcast and have it interrupted by the navigation though; that's how it works on my 2015 Kia Forte.