I have lost sound on some channels but not all. I have no sound on channels 521 to 600 (mainly Eurosport and BT Sport), on most of the other channels seem to play sound without a problem. I have rebooted the box but that has not made a difference.
Just to clarify, on these Channels with no sound, there is nothing, no noise, no background squeaks or hisses what so ever, video feed is perfect, it is just as though somebody had muted the channels (checked, no they have not). or unplugged the speaker.