This is kind of a newer setup experiment for me, but when I try using a Boss SY-300 to scroll up and down through presets in two H9’s, the program numbers change just fine and the active lights stay on, but the audio disappears from both H9’s. The first H9 shows a signal input, but no output. Of course the second H9 shows no audio in or out. When I hit the active button for bypass, I get the bypass signal just fine, hit the active button again, the active light comes on, and back to silence. I have to power off the H9’s to get them working normally again. Both do the exact same thing.
I have used a Tech 21 Midi Moose on the H9’s without any such issues, but I would like to shrink the footprint a bit. I am digging in the SY-300 to see what kind of signal it is sending that is causing the issue, but what is weird is I can’t find the parameter in the H9 that might be being messed with by the SY-300. Both H9 software is up to date. (One Max, one Core)