Question, and there may be a stupid answer to this, but I recently got a CPS3 and am using a kick harness with the HAS for the first time. HK doesn't work on the 1p or 2p side, but all the other buttons work fine on both (including 1p and 2p MK which I think is also on the kick harness).
I've tried different controllers (my DB15 Octopus and a couple of Saturn sticks, PS4 controller), and different adapters (native DB15 stick, your Saturn adapter, the The kick harness I got from you doesn't have any obvious visible issue, and given it's so simple, I would think I could easily see an issue if there was one. I've tried plugging into my JAMMA extension and directly.