MyBook Duo thunderbolt not working after upgrade to MacOS Sierra

MyBook Duo W08UP80040JSL-00 is not showing up after I upgraded my Macmini6,2 to Mac OS Sierra 10.12.1 (16B2555). Drive is plugged in, has the light on and sits between the computer and my main monitor. Computer is fine and monitor works if I plug it straight into the computer. System report shows no controller detected on the thunderbolt bus.

Rebooting the OS made the drive show up again. Very disappointing.

By “rebooting” you mean a full system re-installation, or just a regular restart cycle?