composit material broken?

[miohn]

HI,

using latest version 2020.1R2.R4

The Composit Material order behaves totally strange.
Please look at the images.

green(Mat 1) should be the base-material and the brown dirt (Mat 2) should appear in the corners, right?
Should be the other way round I think!

And now with a 3. Material (Mat 3 for the corners) everything gets messed up!
Suddenly the 3. Mat becomes the BaseMaterial, the 2. Mat becomes the EdgeWear and my initially
1. Material (the green Base) is totally gone.

What I'm doing wrong?

Thanks
Mike