Fragment when merging shapes

I'm trying to use the Fragment option under Merge Shapes, but it's not working as I expected.

I have four donut shapes with a circle overlaid across them. When I apply Fragment, instead of splitting the circle into five separate pieces, it removes the donut portions from the circle and isn't fragmented.  I want the center shape removed and the ellipse shape in the donut to remain.

Am I misunderstanding how Fragment works, or is there another way to achieve this?