Mesh rendered black when roughness is 1.0

Hi everyone,
I am trying SkyLight as the only source of light in a map.
Whenever I set a material roughness to 1.0 the material appears fully black, despite any colors in diffuse map.

When I add any other light source ( I added directional light source ), the material appears normal.

I am pretty new to lighting and I want to know what the hell is going on here!

Is the skylight static, stationary, or movable? is the object the material is applied to static / stationary / movable?

Here how it is:
When SkyLight is static, all objects are black even if they are static or stationary.(The OP issue).
When SkyLight is stationary, all objects are properly colored, whether they’re static, stationary, or even movable.
When SkyLight is movable, all object again are properly colored.
(I didn’t forget to rebuild light every time).
Static light is the least expensive. So even if only stationary is the one to go with, then it is still a problem performance wise (not as big as I thought though).

I don’t know. Is it a template-based scene? or did it start from an empty level?

Not a template. I started from an empty map.

Sounds like a bug if all the objects have roughness 1.0. If some objects aren’t at Roughness 1.0, then there’s a few potential causes:

  1. Lower Hemisphere is Solid Color (default black I think) is enabled. This can result in bounced skylight lighting picking up color from the lower hemisphere and applying it to the objects in the scene. Not as likely, but possible.
  2. Something is wrong in the material graph of the affected objects. A node isn’t connected, the wrong blend mode and/or shading model is in use, color is set to black…
  3. The skylight’s “Affects World” setting is disabled.
  4. If there’s a post process volume, something in it is set such that it’s causing the objects in the scene to render black (to check quick, disable “Unbound” in its settings, which makes it so the volume isn’t blending with the entire world…then look for the setting that’d be causing it, such as global illumination or other Rendering settings).

Not sure what else to suggest for now. Submitting a bug report might be a better option if not getting a solution fast enough.