I'd double check that you don't have the Input or Output Volume of the H9 mapped to a MIDI CC message. We had a problem in the past where MIDI bank change messages were being misrecognized as MIDI CCs and muting the H9. In H9 Control you can check this by going to Pedal Settings in the bottom menubar, go to MIDI Settings, and go to Assign MIDI CC messages to pedal functions.
