That's because gimx didn't pass authentication signal of this controller. Gimx can actually work with any controller, but Dualshock 4 is required just to pass authentication signals from it. If you won't do it - you will get disconnected.After compilation with no error, I can use gimx with the Gator Claw, but after 8 minutes it's deconnected
As for hori - I didn't check the source but I suppose it supplies same signal as DS4. That's why it's working.