I recently updated my Imac to Sequoia 15.16.1. Not it seems that I can't unlock my computer with the keyboard any longer and in the settings for 'Touch ID & Password' the setting is greyed out and can't be turned on.
iMac 24″, macOS 15.6
Connect the keyboard directly to the computer with a cable. Make sure the keyboard is ON (slider on the back).
Does the Touch ID in System Settings become accessible?
If not, try turning the keyboard OFF, wait a few seconds, then turn it back ON.
If you're using an An Apple Magic Keyboard, try going to Settings, Bluetooth, and disconnect your keyboard. Then cycle the power on the keyboard and reconnect it to see if that may re-establish the connection and fingerprint key.
Can't unlock my Imac with fingerprint any longer
