Unlocking new Mac not working with Apple Watch I've grown accustomed to the convenience of being able to unlock my MacBook Pro with my Apple Watch, but I just got a new Mac Mini, and no matter what I do, it is not unlocking it for me.  

I have checked "Use your Apple Watch to unlock apps and your Mac" in System Preferences → Security &amp; Privacy → General.  And I am able to use my watch to unlock (e.g.) settings in the Privacy tab of that same System Preferences pane, like Accessibility settings.  I just can't unlock the computer itself.  

What could be wrong? Why would this work on one computer and fail on another (newer) one?
It seems as if this setting is not honored for OS-level access until after a reboot.  It surprises me that Apple failed to note that in the UI.