I did some more test and found out in my case the problem persists.
I’m having Hardware Raytracing off, with volumetric fog on. In the light, having Cast Volumetric Shadow on, and Distance Field shadow on or off. Now regular spotlights could work correctly with light ray blocked by walls.
But I’m making a searchlight from top of a mountain, lighting towards player pawn in distance up to 350m. So I need the light beam and lit area visible at 350m from the light source, and the light beam almost like a cylinder.
So the setting for the spotlight would be at least
intensity: 500 lm
attenuation radius: 38000
outer cone angle: 0.7
And these 3 settings are the key to make light cut through anything within the range below half of Attenuation Radius, as long as the Intensity higher than 100 lm while Outer Cone Angle lower than 2. Seems there’s a blance there, felt like the the density of the light particles reach a level, it will cut through walls.
Is there anyway to stop this particular light to go through wall? If no, then maybe my only option is make the Attenuation Radius dynamically based on hit to the surfaces.