This Tip in undoable so save your scene first.
Select one surface in your scene, doesn’t matter which. Open Surface Mask Creator and set it up as in the image below.
You will be asked to confirm the removal of shader based surfaces. Click Yes. Then it will either do two things start to render or just stop. Either way we want it to stop. So if it is trying to render a mask then cancel it.
Then This time select your surfaces for the proper mask. Open Surface Mask Creator and leave it set on “Selected Surfaces” but Uncheck the Custom Shader Check Box, then Render.
I have not had any issues with doing like this. So hope that helps to at least use it.
Click thumbnail to see full-size image