Just upgraded to v6.1 from v5 and the Shadowcatcher in v5 worked not only as a Shadowcatcher but, as a mask of sorts that would mask out objects. In other words you could cut a sphere in half with the Shadowcatcher as a plane. This doesn't appear to be working the same way in v6. Am I missing a setting or something?
Right. We have changed the way the Shadowcatcher layer works in version 6. If you need an invisible floor plane, simply duplicate your existing Shadowcatcher plane and keep the new plane in the same position as the Shadowcatcher plane. Then, apply a Matte material onto the duplicated plane and it will mask out the other objects beneath the plane.