How does Surface.differences for many surfaces

Hi all,
I’m a newbie, i trying to subtraction sufaces of colum with each other but have a warning.
Do you have a solution for this?
Thanks!

Could you upload a sample Revit file?

I did not any warnings from Surface. Difference Node.

My file 191Mb, i can’t upload this.
Can you explain to me, I’m still received from node “surface.differences” but something is “null”, i don’t understand about this?
Thanks!