When cutting this corner cabinet, a strange thing happened. One mortise didn't get cut. All the other mortises along with their matching tenons were cut. I've attached the cabinet along with pictures of the cutting results. This was all done using ShopBot Link.
I have tracked this issue down to face frame (left and right stile) outside scribes existing with corner stretcher tops. If you remove the scribes, the dado will then get created. If you can live without the scribes for now, you can get the dado to cut. I will get this listed and resolved. Sorry for the inconvenience.