Only your newer tech will say it works all the time so always have the optical link handy.
Netflix wrote the app so ask them about the app specifics.
I think you have to get heavy handed with the makers on this one. They don't want to sit down and discuss why this happens and I can't reply to every post and repeat the prior discussion such as
You have the best hookup but have to fish around the netflix app to see if it has some setting about audio.
Need help connecting home theater. Have Sony STR DH720 receiver, LG 3d Smart TV 55 LM6700 and LG Bluray LM 6700. Have HD cable tv via Motorola cable box. All have HDMI connections. Both the receiver and the TV have one ARC connection. My understanding is that ARC can go both ways, so that with the Smart TV applications, the sound would also be transmitted thru the receiver. Alas, when I connected this way, received TV sound thru the receiver, but not the apps like Netflix -- I needed to change the output to the TV speaker to get any sound. LG says that ARC is not designed to go both ways, that is why this didn't work. I don' t believe this is true, but did what they said and got a digital optical cable to send sound from the TV to the receiver. With this, I get no sound going to the speaker. PLEASE help me with the best way to hook these up and get sound from cable TV and the TV apps through my receiver to the surround sound speakers. Including how to set the receiver (hate the menu on this thing!)