i use Unreal 4.14…
as i said above, the gamepad is working perfectly all the time in viewport, and any game that support xinput gamepad and its “hot-plugable” plug and just work
but in play/PiE/any preview/launch modes and packaged project, the gamepad is ONLY WORK when i plug it before even turning on pc, after unplug and re plug again, the gamepad suddenly not work anymore, soo its like the gamepad is not “hot plugable”, but remember its still works perfectly in viewport and any other games