The one that didn't work was purchased on Amazon. It was a Wersi usb to 5 pin midi adapter cable. What I didn't realize was that it was for PC and Mac. The ad implied that it would work on Ios but it did not. It would only send 2 out of 3 PC changes as verified by a midi monitor.
My solution was to run a camera / usb adapter from the Ipad into a USB A to USB B cable into the HX Stomp usb port, turned on midi Thru and sent that to the first H9 with a 5 pin midi cable, then out of that with a 5 pin midi cable into the second H9. Works great. Just make sure on the HX Stomp that you have the Midi setting set to send usb /midi and not just midi.
Thanks
Matt