Is this about setting transcoding quality or selecting a specific version/copy/resolution of a show you have (“Play version”)?
For me, “Play version” always plays the video on the local android-mobile or plex-web client, and using the default Play button plays the video on Chromecast but auto-selects some version I do not want to play.
It seems this bug has existed since 2016. Did you have a different experience that this was supported at some point recently?
