TouchID option not displayed / stops working
Solution 1:
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 & 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.