Same here - PS4 > TV > Optical > Receiver - works perfectly for games (even dts), Plex App only puts out stereo, and the quiality is pretty ordinary. Tried direct hdmi connection to receiver made no difference.
Same as the Sony TV android app, no 5.1. Kodi android app does 5.1 no drama on the same setup.
Thread seems dormant - is anyone even looking at this?