When floor(ceiling) texture/color and ground(sky) texture/color are different and door_elevation=0 (or door_elevation+door_height=wall_height) then doorstep (upper doorstep) has ground (sky) texture/color as in picture



If I increase door_elevation (or wall_height for upper doorstep) by 1 millimeter then picture is fine.

Emmanuel, maybe it's better to have 1 millimeter elevation as default for all doors/openings?