Need to do a inverse XREF clip. Have tried numerous times with no luck. Can someone provide a few hints?

Title says it all.  I have a large XREF that I want to create a blank spot in the middle of to put another entity.

I can insert a XREF with a rectangular boundary which clips everything OUTSIDE the box.

When I type I to create an Inverse clip at the "Specify Boundary Option" prompt, it returns

Default: Rectangular

and brings me back to the "Specify Boundary Option"

Hitting return and choosing a rectangle has no effect on the Xref except it now has a boundary attached to it.

Help?

Quick, please, I'm stuck.

Thompson