Electronics Repair Questions? Ask an Electronics Technician
Your TV have a setting that disables sound to the TV speakers when using HDMI.
Try temporarily disconnecting the HDMI cable that goes to the AV receiver and let me know if you hear audio from the TV ok?
This can happen if Netflix is outputting a format the AV receiver doesn't understand, so you end up hearing no sound at all.
There is no setting on the Panasonic that will change the audio format - if the TV is able to process the audio signal but the AV receiver is not, this proves that it is a formatting problem.