The Netflix app may need a setting for audio changed. As there are some thousand TVs out there and Netflix writes the app, ask Netflix where the sound setting is.
I have my cable box, PS3, and DVD player going through my receiver with HDMI cables, which all work fine. When I try to use the Netflix app built into my TV, there is no sound just a picture. I tried to adjust the audio settings on the TV, but nothing works. Any suggestions?