Moved you to a new thread, so you don’t get lost in the mix of the other one.
Nvidia Shield Audio: Leave it at Auto.
Plex app: Passthrough = HDMI.
I think you also have to disable Dolby Processing if the setting is available on your Shield.
Which Nvidia Shield?
Only the 2019 models support Dolby Vision. The earlier models do not support Dolby Vision.
Hopefully others can assist with any Shield specific settings (there are no Plex specific settings).
My Shield is a 2015 model and does not support DV. I do not know if there are any Shield specific DV settings.
