Face Id not working / failing

Hello,

I got my iPhone X on release day. Setup Face Id and has been working great. However, in the last 2 days it has completely stopped.

- The first time, it wouldn't read my face at all. I disabled Face Id and tried to scan my face. Setup didn't work until I rebooted the phone.

- Now it stops working every 2-3 hours for no reason. Just randomly.

- I reboot the phone, and it starts working again.

- Phone is clean. No case. My face is normal. No change in the last week.

- Turn off "requires attention". Still nothing.

Any ideas?

Thanks