Thanks maparizeau! Your answer pushed me to the right direction.
In line 23 I checked for the Number of elements on the StaticMeshComponent:
CompMats = EnvironmentMeshComponent->GetMaterials();
I logged it, and it did spit out “1”. That obvioiusly couldn’t be right, since I have multiple LODs. Instead I should have checked for the Number of material elements on the Mesh of the StaticMeshComponent:
CompMats = EnvironmentMeshComponent->StaticMesh->Materials;
Now it seems to work perfectly. Thanks again!