Audio not playing correctly over lightning digital av adapter

We recently bought a lightning digital av adapter to use in a car. The car seems to only be playing the left and right channels of the 5.1 mix (at least that is my best guess based on my post background and what I am hearing through the car speakers). Is there a way to change the audio on the movies playing in the TV app to 2 channels? I am using an iPhone X, most recent version of the iOS, and I have tried a couple movies.

It’s a 2017 Discovery and there are multiple audio settings (4 total) and I have tried each. Stereo will get more of the dialogue, but it’s still not right. The Dolby, Meredian, etc aren’t getting the dialogue (center) at all.