I know this is only like 2 years late, but I just ran into this, and wanted to post this in case anybody else came upon this thread looking for a possible solution.
My shape layer was in fact showing a path I just couldn’t see it. I was looking at the anchor point of the shape itself and not the layer. I had a really small circle I had zoomed in to animate. I inadvertently moved the circle to the position I wanted to start my animation, and then when I animated the layer, the circle was about 500 pixels off the layer anchor point. The circle was far enough off the motion path I just couldn’t see it on screen. Super derpy. That is all.