I have this same issue. In one instance I made a new simple sphere that was rigged in the same manner and to fix it I selected the mesh that was driving the wrapped object and there are some new attrs that are created called smoothness and dropoff and if I set the influence type to 1 and adjusted those other values it worked, but with my actual rig that doesn't work at all and it looks like it's some kind of bug, either way it IS freakin' annoying.