I use a Sky Box and an amplifier as sound outputs, with the volume on TV set to zero to avoid an echo. This is fine when I watch TV programmes with the sound output set to either TV speaker or optical. However, I get no sound when watching an app (putting the TV sound up plays through the TV speaker but only on the TV). I have done the sound check and it plays through the amplifier. Furthermore, it makes the normal beep sound when selecting an app. This is a new problem; there didn’t use to be an issue.