Just got FIOS and dolby surround sound only works with sd tv. When I'm on hd tv channels, I either get no sound or just the background music or occasionally all the sound. It often changes when the show goes to commercials. I have been through all the supposed fixes with FIOS. They didn't work. They think it's the cables but I have swapped out cables I know work and it made no difference. When I use Roku or Apple TV the sound is fine.