I suspect the issue is that the TV OS version is webOS 1.0. The support for advanced playback features is limited, and this probably include audio track selection. According to the specs, Media Source Extensions (MSE) was only available from version 3, and even that was only the draft standard.
We know that the web0s 1.x and 2.x version have issues with subtitle switching, and this will most likely be the same issue.
This older OS version/model will also be why the app is somewhat sluggish
Edited by SamES, 02 August 2019 - 08:00 PM.