I think you have a similar but not the same problem its more likely some form of HDCP that's causing the problem with HD or the signal is not there in HD that would fire the sound bar .... from quick searches I find people mentioning the soundbar is 4.1 compatible ... 4.1 is not the same as 5.1 and most HD stations use 5.1 dolby as the format.. could that be the actual problem you're experiencing?I am also having this problem. The optical cable is connected to a Vizio sound bar. But then i watch somthing DVR'd from HBo i get no sound. (but it works from the tv speakers as it is connected through HDMI) Chated with tech support they told me to restart the receiver, then sent me to level 2 support and they asked me to unplug the cable and plug it back in. Then said they would send a tech out to check this out. I then told them that they sucked and told them i was not going to use my free tech visit on this issue and i would just look it up on google. So here i am. Im guessing we have not figured this out?
UPDATE: this is ALL HD channels. all sd Channels work fine.