Blend 4 material attributes Error

Hey everyone,

I’m currently creating a master material. Unfortunately, an error has now occurred for which I can’t find a solution (screenshot: Error).

I want to blend 4 material attributes (Screenshot: Material). However, as soon as I have connected everything correctly, the material went default and when I try to save the material, I get the error (screenshot: Error).
If I now use one of the materials twice (screenshot: No Blue/No Red), the material works again. But whenever I use all 4 material attributes, I get the error again.
Another thing is, if I change the blending mode (Screenshot: Change Blend), then the material also works. However, it then no longer works the way I want it to.

Does anyone know what the problem is? I have already looked in my project settings, SM6 is activated.

I hope someone can help me with this. Thank you very much