Unreal Volumetric Lightmaps - How to properly use them?

hey, thanks for the help. Though, I am confused why the doc behaviour looks so different and so much more optimized. See here:

As you can see volumes spawn only within the lightmass importance volume and increase nicely with more samples around the actual static geometry. On my end, its all same and goes beyond my lightmass importance volume somewhat with some bigger ones being further away. Which I knew why I dont get dense volumes around my geo :confused: