The one-shot switch of MIDI device panels sends the value on both mouse-down-click and mouse-up-click when set to parameters assigned to sysex (maybe other parameter types, too, but I didn’t test that.) The result is the sysex message is sent twice for one mouse click of the switch.
Is this a bug? Is there a way to get the mouse-up to do nothing so that the click only sends the sysex message once?