Hi aronortega,
I understand how this is frustrating. You have already tried most of the options I was going to recommend. I have seen circumstances where the H9’s don’t like to appear early in a MIDI daisy chain, but rather, operate normally when placed at the end. In every case, using the MIDI Thru box as you’ve described fixes the problem, but nothing jumps out at me in your case. Have you tried swapping the H9’s where the one that’s currently acting as your PRE you program as your POST and vice versa? That might help determine if one is problematic or if it has to do with something else in the programming.
