noise in the tuner mode (Signal = muted)

  • Hello
    Today i recognized another Problem...
    When i selected a Rig with an overdrive pedal (green Screamer) and i select the tuner mode (with muted signal), there is a noise (power head into a guitar cab).
    When i deactivate the overdrive in the kemper, there is no sound...
    (btw i checked different ground lift combinations")
    What am i doing wrong ?


    Best wishes
    Simon