In your video when the sides of the head are flattened, you use the transform gizmo and drag out, sort of a cylinder shape and then pull the sides in. When I do this, it creates two inverted cone shapes, instead of a cylinder, so the result is a sort of jagged pancake stuck to each side of the head.
I guess I can smooth it out later. But, do you know why I get inverted cones, instead of a cylinder shape?
Gecw's solution of apply all transforms IS the fix to this, no bug.
May we exalt their name on the highest!