My BT HD Pro Netflix App outputs DD 5.1 via optical to a 5.1 amp with an LG Nanocell TV connected via HDMI but not when it is connected to an older Panasonic Plasma TV
Presume the Netflix App it is doing some form of handshaking via HDMI to check compatibility
This then determines what is sent via both HDMI and Optical
You don't appear to be able to get DD 5.1 from the BT Box Netflix App via optical independently if your HDMI receiver is not compatable
That is an error in the Netflix App
Amazon Prime has no problem
I have an ‘older’ tv. There are no hdmi inputs for example. My BT box is plugged directly into my quite new receiver Arcam AV41. Amazon doesn’t do Atmos for me.