I just got a Sony 55x900f (and I have a Razer Leviathan audio system). I'm still on Android 7, btw.
I downloaded a 4k HDR video with DTS audio and noticed that no player could output sound (I tried the default Video app, Kodi, Mx Player and VLC).
After searching some more I noticed that VLC has an option to pass audio directly to the sound system. With this setting on, I can listen the audio perfectly. But, VLC keeps stuttering from scene to scene.
The video located on a USB 3.0 HDD (connected to the only USB 3.0 port available on my TV), I'm not sure if this is an issue with a possible slow HDD because the other apps can play the video without stuttering (but of course, without sound).
Do you have a 5.1 sound system? Because if not, disable "passthrough audio" in your video player(s) and they should play DTS just fine.