Impossible to move stuff along Z (Vertical) axis

This one really bothers me, since it was a feature I wanted to experiment with. When I first downloaded the game, I was able to move cars and objects vertically in the editor to drop them from a high altitude. After about an hour of playing around with the game, I spawned a tire stack, moved it high up, and dropped it onto the roof of the Ibishu Covet. I did this 3 times. On the fourth time, the game crashed. When I relaunched it, I couldn't move anything along the Z (vertical) axis in the editor. When I try, it moves a random grid plane upward, but leaves the car/object at the same Z position. Has this happened to anyone else? If so, is there a way to fix it?

 

I officially love you tdev. Thanks! That fixed the problem!