I'm trying to make a Boss-Extrude feature using "Up To Next", but instead of "stopping" the extrude at the next surface, it continues to the furthest part of the part/body, completely enveloping the body:

I did not expect a solid extrude straight through the overhangs.

Why do this happen? And any suggestion on how to achieve a true Up To Next feature?

This was the setup:

And this was the result: