Question When I hold down the TAP TEMPO button my signal is muted. Why is that

Holding down the TAP TEMPO switch allows you to enter Audio Tapping. This function lets you to set the tempo using the input signal. This is how to use it:
  1. Press and hold the TAP TEMPO switch. When the outputs are muted, play steady short 1/4 notes on your instrument. The TAP TEMPO LED will indicate the tapped tempo.
  2. Release the switch again.
  3. That's it (there's no step 3)!