So if you use a MBP in clamshell mode with an external TouchID-equipped keyboard, you might have noticed that whenever you plug the MBP into your desktop setup, say via a TB hub, you won’t be able to log on with TouchID on initial connect. You’ll be required to type in your password.
However, if instead, you then hit esc (sending the MBP back to sleep) followed by any other key (waking it for the 2nd time), now TouchID will be available for authentication.