If you want, you can send me your project by email (support@infinity-code.com).
I will check it and give you advice on how to fix it.

To be clear:
I don't need your work project.
Any temporary project where the problem will appears is enough for me.

Hello.

When you have a black map it usually means your scene has no lighting set up.
You have three ways:
1. Use Ambient Lighting.
Window / Rendering / Lighting / Environment / Environment Lighting / Source - Color, Ambient Color - White.
2. Use Unlit shader.
3. Adjust the lighting in the scene.

No, I have a light. It's still black

When you have a black map it usually means your scene has no lighting set up.
You have three ways:
1. Use Ambient Lighting.
Window / Rendering / Lighting / Environment / Environment Lighting / Source - Color, Ambient Color - White.
2. Use Unlit shader.
3. Adjust the lighting in the scene.