I have made a 3D elevation surface in ArcScene. See attached 3D Arcscene.JPG. The extrusion that makes it look like a cut-out landscape was achieved by extruding a polygon which represents same extent of the elevation layer. I didn't have any issues with this.
I tried replicating same thing in ArcGIS Pro 2.2 but it doesn't seem to work. The extrusion doesn't take off from the elevation surface no matter which type of extrusion is used. See attached 3D Pro.JGP. I am extruding to -4 meters.
Any help pls. Am sure it shouldn't be this difficult.