Toon Boom Studio: no pressure sensitive stylus on dual screen

Found something very odd about both Toon Boom Studio 4 and 6:  when I run the application while Windows is in dual monitor mode, I DO NOT get pressure sensitive on my Wacom stylus.  Turned screen mode to single monitor, and pressure sensitive comes back.  Not the end of the world to me since I can live with one screen, while I run other application on another PC.  But it's still kind of odd.