Using "relative to scene" elevation mode to overlap two polygon layers

[tcyd]

Hi there!

I am trying to overlap two polygon layers (same layer but duplicated) in ArcGIS Online Scene Viewer.  Both layers are with 3D extrusion according to the attributes.  Once I set the elevation mode to "Relative to scene" for the the layer on top, the extrusion of the top layer deforms.  However, when I set the elevation mode to "Absolute height", everything is displayed correctly.

I have searched and it seems there are only mentions about "Relative to scene" elevation mode for point layers.  May I know whether this functionality only confines to point layer and there is no other way to achieve what I want? (overlapping the same layer, via different attribute)?

Have a nice day!

[tcyd]

For those who are looking for a workaround, I eventually shrinked the polygons of my top layer a bit (like 0.99x) then the "relative to scene" works perfectly - the top layer is fully on top of the bottom layer.  It is not correct as the shape has changed, but it achieves what I want visually.