It is very strange. I use 10.14.6 on my Mac and H9 Control works fine via USB connection.
I'd suggest:
1. Try removing the H9 in your Audio Midi Setup and so the pedal will reinitialize in the Audio MIDI Setup when you connect to your H9 next time
2. Delete H9 Control and reintall it
Does H9 Control recognize your H9 if you click "Manually select a device" -> "Connect via MIDI" -> select your H9 as MIDI input and output and then click "Connect" ?
Let me know if any of these works
