That is actually the exact issue. If issue was somewhere else, I’d have problems with Sky Light inactive.
From skimming ArchViz section I see people use 4.11.2 and not 4.12.5 or 4.13. Plus in ArchViz scenes floors are enclosed inside the walls and not placed as in my scene. If I model my “crypt” in 3D app and not assemble it in UE4, I will have no issues with lighting.