Your 3D model with normal maps may be invisible in complex shaders if the normal map’s UVs are mismatched, it’s not connected to the right shader slot, or its format (tangent-space vs. object-space) doesn’t match the shader’s needs.
UV mismatches mean the normal map isn’t aligned to your model’s surface, so the shader can’t apply it. If the map isn’t linked to the correct shader input, the shader won’t use it. Using the wrong format breaks the shader’s calculations, leading to invisibility.
Fix this by checking the shader’s required format, reconnecting the map to the right slot, and verifying UVs are unwrapped without overlaps—these steps usually resolve the issue.