Problem when two conditions cross

I have the plugin installed and it works fine. But there is a problem when conditions are crossed and I don’t know how I can fix it.

I have products of a special category marked so that they can only be shipped with a specific transport agency. The rest of the products are sent with a different one.
The problem arises when someone orders products from both categories. The system indicates that there is no transportation agency available. Does anyone know how I can fix it?

The page I need help with: [log in to see the link]