I seem to remember reading about the Helix using CC #32 for Setlists. In the H9, CC #32 is mapped to Input Volume by default. Sending a low CC value to the H9 would effectively mute your input. If that’s the case, you can reassign Input Volume to another CC#, or No Mapping, if you’re not using it. In the H9 Control app: [Pedal Settings -> Assign MIDI CC messages to pedal functions -> Input Volume].