I submitted diagnostics for this but thought a bit of explanation was in order. A 4k HDR10 file will not play correctly on an Nvidea Shield device connected to an HDTV that is not 4k. Results in a green screen with video artifacts across the top while the audio plays normally. Playing the same file back using a browser client on win10 pc, the file plays normally. Tried several similar files this morning with same results so its not a one off.
Playing the exact same file in Plex from the same storage location it plays fine on the shield. Something up with the transcoder in Channels.