The upper surface of my clay body is bounded by a surface-loft, which is hidden because it is inexplicably tesselated.

An excavation is cut-extruded into the clay.

An LC on the remaining upper surface of the clay body, selects in blue the "donut" that I want colored green, leaving the cut faces in orange.

So far so good.

When the Selected Geometry is applied at Component level, all faces of the clay body turn green.

When the Selected Geometry is applied at the Part level, nothing turns green.

How can I get just the selected area to turn green?