ProBoolean applies operand material to entire object

[Anonymous]

I am simply applying a subtraction modifier in ProBoolean to two operands and when I have "Apply Operand Material" selected it recolors the entire object instead of just the new faces created. I checked in another file where I did exactly the same thing, and that works fine. But here it does this. Does anyone have any idea what might be the issue? The only difference I can think of is that the shape is different in this.

[Anonymous]

Check your material settings. If you have a multi layer material on the object it can cause Proboolean to do that.