Duet for iPad & Mac not recognized in firmware updater

Before running the the firmware updater:

• Unplug your Duet from your Mac
• Now hold down on the Duet's encoder knob for 20 seconds while plugging back in to the Mac.

This resets the unit. Here's a video on this process: How do I reset the Duet 2 or Duet for iPad & Mac?

• Now launch the Duet firmware updater app from the latest Duet installer and update the firmware.