Clipped geometry inside CartographicPolygon casting shadow

Cesium for Unreal
1

Hi,
I am using a CartographicPolygon to hide cesium buildings inside of archviz project area which normally works fine.
But in my current project the hidden geometry inside the polygon still casts indirect shadow onto my geometry, which look somewhat like ambient occlusion:

Cesium deactivated:

image
image1295×783 53.8 KB

Cesium activated:

image
image1277×787 102 KB

Using UE 5.3.
Any ideas are welcomed, thanks!

2

Am I understanding correctly that you don’t have this problem in other projects, only in this one? Are you perhaps using a world position offset in this project? I found this old thread on the Unreal Engine forums. It’s not very conclusive, but it suggests there might be an issue with masked opacity and a world position offset.