TouchID option not displayed / stops working
Today I finally figured out how to fix this without rebooting.


Go into System Preferences -> Touch ID
Check or uncheck the boxes under "Use Touch ID for". 
When you check or uncheck either "Apple Pay or iTunes &amp; App Store", you will be prompted for your password. Enter your password.
Finally, reset the checkboxes to how they were before.


This will (I assume) restart the Touch ID service and it should start working again.