@Turknor
Hi there! while the occlusion is not perfect within the nebula-sphere, it must at least work for objects in front and behind it accurately. The EnvironmentOcclusion parameter is set in blueprint, so to show the changes during PIE, go for this parameter directly by selecting the Material of the RenderSphere in the NeblaActor in the level.
On the other hand i was able to reproduce the issue and like you said, translating the nebula away from the center leads to those occlusion artifacts. please add the ‘subtract ObjectPosition’ after the ‘CameraPosition’ node within the Mat_DisplayNebulaBuffer material. also make sure that the Material domain is set to surface.
hope this helps 