Reflectivity on a Black surface

From a user:

I've got problem with rendering of black colour (mostly on walls or added graphics).
This colour appears to be like "black hole" and it does not reflect any lights, while all other elements with other colour (like green for example) become highly iluminated.

The problem is a result of having the Black material set to be "Metallic". The Metallic setting forces the reflections to be the color of the material. In the case of a black material, this causes the reflections to disappear completely.

Here is a rendering of 5 colors, all set to be reflective and metallic:

If I edit the Black material and uncheck Metallic, I get:

If I uncheck Metallic on all materials I get:

That is probably what you want to do. Then you can adjust the reflectivity of all of the colors and get a more realistic rendering.