I found a small “issue” regarding Lumen GI and Stationary SkyLight, it seems both aren’t compatible. All my SkyLights were Stationary, and when I disable Lumen GI through Scalability, my Skylight stops working and becomes black, but it works if I set to Movable.
That’s a great find, and is now fixed for 5.0 release. When Lumen is disabled by scalability it shouldn’t be affecting the rendering at all, but it was in the case of Stationary Skylight.