My 2018 key start Elantra has a dealer installed factory remote start. The manual provided with it tells me, that once the car has been started via the remote, I can unlock the driver's door by pressing the remote's single button twice. It says that I can then unlock the other three doors by pressing the button twice more. The driver's door unlocks as expected, but I cannot get the other three doors to unlock consistently. I've tried every possible combination of press-press... pause... press-press, and none works every time... I can open all four doors, perhaps 10% of the time, with the remote.. Any suggestions??