Sonata I45 (LF 2015+) :: Transmission Won't Go Into Any Gear When Stopped At Intersection

I recently inherited this car from a relative, I had it and two other vehicles she owned towed to my house about a week ago. The Sonata has under 1000 miles on it and I found a stack of repair orders from the dealer where she complained that the car wouldn't move or where it had been towed after getting stuck at an intersection while driving.

What is happening is that when I get in the car, with the engine cold, it starts up and drives fine. Then with no pattern or warning, when I stop at an intersection, the transmission acts as if its in neutral. It won't go into any gear, regardless of where I put the shifter. Its got the 2.4L GDI motor. and an automatic trans.

I had to tow it 5 times now. I took it to the local dealer and they found nothing wrong, no codes, and couldn't reproduce the problem. Yet when I went to pic it up, it did it a block from the dealer, I had to push the car to the shoulder at the light. I walked to the dealer, they had a tech come out to the car and by the time he got there the problem was gone. I took it home, and when I got home, I shut it off, then tried starting it and moving it again and nothing, it wouldn't move at all, no forward, no reverse. I find that if I cycle the key, on and off, sometimes the issue will go away instantly. I also never does it cold, only after driving it a bit. It has never done anything wrong while driving at speed, only when coming to a stop and trying to move again.

When it happens, the shifter moves fine, the engine revs and there are no warning lights on the dash, it just acts like its in neutral regardless of what gear the shifter is in. It doesn't creep or pull at all, there's no movement at all when it acts up and I have to drive it to get it to do it, it can idle in the driveway all day and won't do it till I take it down the road and come to a stop and try to start moving again.

Out of frustration I bought a scan tool to see what's up but as long as the scan tool is plugged in, it doesn't act up. I've been driving it for two days without it doing it. Thinking it may be just coincidence, I unplugged the scan tool, took a ride and it did it at the first intersection, I had to shut the car off, plug in the scanner to get the car back home. I called the dealer and was told that this was impossible.

I'm starting to feel like I'm on my own with this one since the dealer seems to not be able to find the issue. I am really having a hard time believing that the dealer can't make it act up but if they're plugging a scan tool in, and driving it, maybe that's why?