Panny Tc-P54G10 Plasma and Yamaha RX-A3000.
I do have the return control on in the receiver and can control the volume, levels and get sound when viewing the normal tv content and get sound through the HT speakers, but it's a Vieracast thing - once I switch it over to Vieracast, no audio. I also have the Vieralink setting to go to HT speakers, not tv. The auto-switching works pretty well, but I'm trying to avoid running one more cable (optical) to the tv from receiver (which seems to be one solution that works) to get sound in that mode. It would seem odd that the audio wouldn't be available via hdmi (ARC or otherwise, unless Vieracast is only send video via hdmi and not audio).
TLS- I tried turning the HDMI outs to off while in that mode and no luck there either (it does turn off the video when viewing normal tv while still passing the audio signal, which is good to know).