Not able to adjust points of a shape

For some reason, AE has stopped allowing me to adjust individual points of shape paths. Here, I have a rectangle shape layer that has Wave Warp applied to it. I would like to make the left half of the rectangle smaller than the right (thus almost making a triangle shape). However I am unable to adjust any singular point. 

I can't get a screenshot of it, but whenever I select the shape layer and try and use the pen tool to adjust the individual points, it won't allow me and instead keeps trying to create a new shape/mask. The Convert Vertex tool does nothing either; when using that tool, if I move any singular point the whole shape moves. I also am unable to convert the shape to Bezier path; that option is greyed out. 

I thought maybe it was because of the Wave Warp, but I tried again with just a normal rectangle shape layer with no added effects and it still wont work. 

For reference, I am trying to follow this tutorial and I do not understand how they are able to accomplish step 8:

Smoke Animation in After Effects | Keyframe Academy - YouTube