I use Light Propagation Volumes (LPV) for dynamic direct lighting, and all materials work just fine except these which use refraction. The target goal is to create rain particles which use refraction with fresnel like in a famous Koola’s video: UE4 shader/fx test - YouTube . Unfortunately, when I drop a refraction material from Content Examples (M_Glass, M_RefractionDepthBias, etc.) or create one on my own, with or without Fresnel material function, it shows no refraction effect while all other channels (defuse, specular, opacity, etc.) are displayed all right.