I have tried to import a 3d object composed of 38 parts (each part has its own material). The problem is that only the first 16 materials from MTL file were applied to the surface shader through multi shader. The rest 22 materials were not connected to the surface shader. I have created another multi shader and have connected the next 16 materials to it. Then I have disconnected the first multi shader from the surface shader and have connected the second multi shader to the surface shader to see what happens. I tried to change materials connected to the second multi shader. The interesting thing is that when I changed materials connected to the multi shader the changes were applied to the parts/materials connected to the first multi shader. For example, when I changed color of the 10th material connected to the second multi shader the change was applied to the 10th part/material connected to the first multi shader although it wasn't connected to the surface shader.
My question is: How to apply the 17th material and the next ones mentioned in the MTL file to an imported 3d object composed of more than 16 parts/materials?