When I try to turn on the Apple Watch unlock feature, I get a message that says: "Two-factor authentication is required to allow your Apple Watch to unlock your Mac. To turn on two-factor authentication, you must first turn off two-step verifcation at appleid.apple.com." So I did just that. I logged into appleid.apple.com, turned off two step, and turned on two factor. But the error message remains the same when I check the box for the unlock feature. I've restarted a few times, waited several hours, same problem. Any ideas?