Plex app version on the Shield?
Have you installed Shield Experience 9.0.x?
There are issues with TrueHD audio on the Shield. See Nvidia Shield Dolby TrueHD playback is borked .
From reading the thread, 8.30.2 seems stable. The latest 9.1 beta seems to help as well.
You can download 8.30.2 from the Android TV announcement thread.
Betas are available via the beta announcement thread.
The “Borked” thread mentions sideloading via adb. A quick Google search for “Nvidia Shield sideload” returns many hits detailing the process.
