I've had the same problem, always after either making the 90º turn backing out of my garage, or backing out of parking slots, and only when I'm in a hurry. I quickly figured out that it's because, due to the hurry, I'm slipping off the brake and/or releasing the gearshift button too soon when shifting to drive. When I'm not in a rush, this never happens. You really need to hold the gearshift in R or D, not releasing the button, for a little more than a split second, or the transmission just registers N.
I think the problem's us, not the transmission. Good thing--we can be fixed without going to Kia service.