Since I am new to the Leaf world I am not sure which car years/models have which features. After a few days playing with the "features" of my 2019 SV with tech here is what I have figured out in regards to the bluetooth:
When I start the car and plug my phone into the car and android auto starts, the radio will automatically choose USB input as the default audio path as part of connecting to android auto. When this happens, I look at the bluetooth settings in my S9+ and the "media" setting is disabled, all other settings are enabled including call audio. When I attempt to enable media it immedietly disables. If I go into the audio source menu on the car and choose bluetooth, it asks if I want to choose a bluetooth device, when i enter that menu the S9 is grayed out and cannot be chosen.
Since audio works (with a delay) through bluetooth, this is not an too much of an issue, and I think the audio quality is better through USB than it is through bluetooth.
What does cause a problem is that for some reason USB connection fails and kills the audio, but the media continues to play. After the connection fails I am able to choose the S9 bluetooth as an audio source. I believe that the USB failure is in the entertainment/nav system for the following reasons: 1. I use the same Android Auto system in a Honda Civic Si and with a Kenwood stereo in my Tundra and have no issue. 2. I have taken cables from the known working vehicles and swapped them around, the issue stays with the Nissan.
So, this might somehow relate to the issues others are having with their bluetooth, if you are using the car's USB port, try disconnecting it and go into your bluetooth settings on your phone to see if media audio is disabled.