Nope, no divide by zero happening. I finally came up with another workaround (something I get to do frequently with this software). Scaling incrementally until I get close to my desired scale and then do the final scale got it to work, and also I had to change the orientation of reference start and end points. Doesn't work in Z direction, but scaling by the same ratio in Y direction does work. Gripper is much more reliable for scaling, but not precise at all. Obnoxious.