Same problem here. Found solution.
I have the same problem. Wanted to watch Netflix through my home surround sound system. Couldn't get the sound to work, so I bought an AppleTV. Tried again today and turned to the owner's manual of my Pioneer receiver. I have my television connected to the HDMI Out on my receiver. The owner's manual says in order to hear sound from your television, you must connect audio cables from the tv to the receiver.
More reason to treat a television as nothing more than a monitor to display a picture. Use another device for apps. Such as an AppleTV, a Roku, or a computer.
A little disappointed, but the picture on my Samsung is amazing. My AppleTV makes up for the apps on the TV.