Dynamic lighting does produce GI! That’s what the volumetric lightmap is for! It’s intended for dynamically lit scenes, or partially dynamic scenes. It’s a form of global illumination. Switch to dynamic, modify skylight to not be so intense, and improve directional lighting (set to movable too) via post process volume(s) and its inherent settings. Turn on ambient occlusion to flush some of the higher contrasts in lighting that don’t look right. A cathedral is often brightly lit in certain small areas, and dimly lit in others, so ambient occlusion can help get that variation and correctly. There’s no faking GI in Unreal Engine. You either get results or you don’t, and when it’s not there, it is highly visible / obvious. Skylight and directional light are both global illumination producers. Check to see if there’s more than one skylight in the whole level (if there’s one that is inherited in the HDRi, and another elsewhere in the World Outliner list, then there’s more than one and that is going to cause over-brightening or other problems). Delete one of the skylights, better to leave the inherited one and adjust it because it’s already connected to the HDRi.