I have not had the greatest success in testing this on my July 2018 MX. I get out of my work late and most of the time the parking lot is pretty empty. The first few times I tried this, the appropriate behavior was to back up, turn, and then drive straight down the row to pick me up. Instead, it drove forward into the parking bumper and tried to drive over it and into a drainage ditch. I stopped it just in time. I think this was software 2019.32.12.1
In another test, it did back up and then drove down the row.. and nearly hit a car in the way, on the wrong side of the lane of parking spaces. I stopped it in the nick of time and walked the rest of the way to the car.
A few nights ago it successfully backed up and drove towards me and picked me up. This was 2019.32.12.2
Tonight the car tried to back up, panicked, and shut down and refused to budge. There is no traffic around. I had to nudge it out of the parking space on reverse summon, let it rest a minute, and the restart the enhanced summon and it drove towards me and stopped where it was supposed to.
Not quite ready for prime time. I hope the car is talking to the engineers and they are trying to figure out what it is doing.