Samsung TVs do not support Dolby Vision.
Plex Media Server does not support transcoding Dolby Vision.
Some Dolby Vision videos have a HDR10 compatibility layer (ex: rip from Blu-ray disc). Plex should play the HDR10 layer of the file.
Some Dolby Vision media, such as DV profile 5, used by the streaming services, does not contain a HDR10 compatibility layer. When playing such media using the Plex Samsung app, you will receive the “color space not supported” message (since the TV does not support the format and Plex cannot transcode it).
Thread with additional info: Plex does not support Dolby Vision
