Sometimes audio is lost when the codec changes from one to another (like stereo to 5.1 or other). Generally, simply swapping inputs back and forth will resolve this. Sometimes turning the 3808 will fix it. I'd try that first and see what happens. If the problem persists, then it's likely a setting in the 3808. If you have the LFE channel, but missing the others is perplexing and I’m not sure right now what could be causing that.
One of the wonderful things about HDMI is a thing referred to as "handshaking". This really means that there is copyright information embedded in the data stream. The devises pass information back and forth to make sure the digital content isn't pirated. Once they are happy it isn't, then the data is allowed to pass. Switching inputs or cycling power makes the devices shake hands once again. I had all kinds of audio issues using HDMI with my DVR. I gave up and ran a coax cable for audio.
