This seems like it should be simple enough, but I can't figure out how to mate a subassembly to a 2D sketch. I'm trying to use the center profile mate between a circular face and rectangular sketch - the rectangular face I'd naturally use has a notch in it, so it's not valid for the center profile mate. When I try to mate the sketch with any other part it shows up in the "mate entities" box, but the mate process acts as if it's not there, i.e. I can have "SketchX", "CircularFace", and "RandomFaceX" in the box and it'll mate "CircularFace" and "RandomFaceX" just fine while ignoring the sketch. Am I missing something?