HI @ATNeo I had the same issue with Rectangle lights, very strange and sharp shadows, also no matter what setting changed in actor details, no effect. As the last option, I changed Lighting quality from Preview to High, in Editor, under Build tab. That fixed the problem. As I understand, Rect lights are not supported by GPU Lightmass, so it uses parallel CPU computation, so changing light and lightmass settings in the Editor will affect the scene.