If all you have is a cut extrude feature, then it shouldn't require a fully defined sketch.

Is this an assy cut?
Is there a error in the sketch?

you can check a sketch for errors by clicking on sketch tools menu and clicking on check sketch for feature, choose the extrude option and it will high light the areas that are causing the problem. two circles on top of of another will cause an error. check and make sure the sketch is valid.