When I share a Scene created in ArcPro as a Web Scene, my ground goes flat. My ground displays correctly in ArcPro and there aren't any warnings when I share. I've tried several things and I can't get this 'custom' ground to display properly in the shared Web Scene. The default 'WorldElevation3D/Terrain3D' does just fine, its elevations display correct when shared. But this new ground won't. What could my problem be?