I email the following to the support address you gave me….
"Hello, My H9 can't be found by H9 Control via USB on my MacBook Pro. I tried the H9 on a friends MacBook and it worked fine. I just checked System Information on my MacBook at it sees the H9 under the USB section. I've downloaded and reloaded H9 control twice. I've rebooted the computer twice. I believe I have followed H9 power up and plugin procedures. Any ideas?"
So for some reason the H9 Control app can't see the H9 (via USB, not a MIDI connection) while the MacBook can. The good thing, it's a software issue and not hardwear!