When creating a material, it turns out completely dark.

Creates a material with two layers. Grass and gravel.
Parameters have been changed in node “Texture sample” nodes: Sampler Source-> Shared: Wrap

In the “Layer Blend” node, the “Preview Weight” of the first layer was set to 1.0.

At the output, I get absolutely dark material, no settings in the preview window affect the result. The material itself on the object looks the same.

I use the latest version of the engine (5.0.1). Updated via launcher.
Please help solve the problem!