As you can see with the corner I whipped up here, the first half of the corner is defined and normal but the exit get has that nasty chop which makes it so tough for track makers to work around.
This is just a circle made with the raise tool, when it is dragged diagonally from the top left to bottom right or vice versa it creates the chop but is fine on the other sides of the circle.
Obviously it's not as bad with 4k terrains or making the map smaller but still noticeable.