Seat belt auto locking retraction not working

I'm trying to install a seatbelt restrained child seat, but I can't get the auto locking retraction to work. I don't think I'm doing it wrong. I extend the belt the full length and let it retract, but there's no clicking sound and the belt can be freely extended. All belts in the car behave the same way.

Model 3 VIN 488xxx delivered in September at Alexandria.

Manual says:

To securely hold child safety seats, all
passenger seating positions are equipped with
an automatic locking retractor (ALR) that, by
pulling the seat belt beyond the length
needed for a typical adult occupant, locks the
belt into place until the seat belt is unbuckled
and the webbing is fully retracted. The ALR
mechanism operates as a ratchet, winding in
slack and preventing the seat belt from
extending any further until it has been
completely rewound. When installing a child
safety seat, engage the belt's automatic
locking retractor by pulling the seat belt
webbing until it is fully extended. The ALR
system engages only when the seat belt is at
its maximum extension point.​