figured out what was going on. This situation happened to me 3 times previously. Previously, I shut off the ignition and the sound came back on when I started it back up. Today, got into the car. Sound came on for a few seconds and then went mute. Looked on the MMI screen and on the bottom, I saw there was a phone icon even though I had not tried to call anyone. Hit the tel button and pressed end call button. Sound came back on. So I'm now wondering if this could be the reason for previous issues as well as other owners problems. Obviously a glitch in system. But if anyone experiences the loss of sound with their B&O, check the MMI to see if there is a phone icon. If so, end call.