Support passthrough on tvOS

Issue: I'd like to playback an 5.1 file. example. The official tvOS VLC app plays it as 2 channel, stereo. I'm getting the same result on the app I'm developing. However other non-VLC apps like Netflix play 5.1 just fine and so does my Macbook using the VLC app and playing the linked example file.

Is this a known issue? or is there something I can do to make surround sound work?

Context: Developing a Tvos video playback app that will play movies streamed from a network device. Much like the current VLC app. The apple tv gen 4 device is connected to the TV through a 5.1 AMP that instantly shows the moment surround content is passed through. The only instance it sticks on stereo is in VLC :(