I had a scan customer come in the other day, and I fired up Makerbot for Desktop 3.3 and it said that the Digitizer was not connected, even though it was. Tried cycling power on the Digitizer, no help. Tried rebooting the computer, no help. Finally I uninstalled 3.3 and reinstalled 3.2 and now it saw the Digitizer and did the scan.

As Geoff would say: [facepalm]