How to get floor shadows in real world with ARCore?

Hello, I am using ARCore and the "ObjectManipulation" example, and when the "PlaneGenerator" gameobject creates a plane (with name "DetectedPlaneVisualizer(Clone)"), I see the material name is "PlaneGrid". I saw that there is other material in their folder named "ShadowPlane". If I asign it to the created plane, the grid dissapears, but it don´t show "transparent shadows" to can see virtual shadows in the real world floor.

If I create a plane manually (Create -> 3DObject -> Plane) and I assing the "ShadowPlane" material, this plane shows transparent shadows like I want to get. Why don´t work with the "DetectedPlaneVisualizer(Clone)" gameobject created with the PlaneGenerator gameobject?

Thanks in advance.