Tahoe: FaceTime not showing Accept or Decline

MacOS Tahoe FaceTime problem.

My mother lives in Portugal with a new M4 iMac, installed last week, and a fibre connection which was installed this week.

if I call her with FaceTime her iMac rings, but shows her no way of accepting or declining the call, as she is used to. I am using an Intel iMac running Monterey on a fibre connection in the UK.

I have checked her Notifications (I use TeamViewer) and her iMac has been restarted several times since the problem appeared.

Any ideas, anyone?