Macbook Pro 2023 - Face-time is configured correctly, but all calls are instantly missed.

This is the second time I'm posting because I tried 2 months ago, but didn't get a single reply and my question was archived.

Macbook Pro 2023 - Facetime can make calls, but cannot receive them.

I'm trying to help my mother with her Macbook Pro. She does not have an iPhone. She used to be able to receive calls on FaceTime without issue, but ever since she got the new Macbook, she cannot. She can call me and everything works fine, but if I call her, it immediately shows a missed call. It doesn't even give an option to answer the incoming call. I've used remote access to test this so I can clearly see what's happening on her end. She just gets a red 1 on her FT icon on the dock.

It is not a network issue because she can call me. My dad also tried calling her from his iPhone, she still doesn't get a notification when they're on the same wi-fi.

Under FT Settings, she's logged into her Apple ID, and "You can be reached for FT at:" is checked with her Apple ID email added, although greyed out.

FaceTime Notifications are on in her system settings.

Any ideas?