Location not shown for one family member using Find My app

I have changed my son's iPhone (from an iPhone X to an iPhone 11 Pro), using a backup and restore from iCloud.

After the new iPhone 11 was working, we deleted both an old iCloud backup, and also the iPhone X from his devices.

Everything is working fine, his apps and content are restored.

Location services, and location sharing are fully enabled on his new iPhone.

Using the Find My app on my iPhone or in iCloud.com, I can instantly see the location of both his iPhone and his AirPods.

All my family member's location are correctly reported under the initial "People" tab, except him:

I got "No location found".

For some days, the location reported in the Finf My app under People tabm, was the place where we did the backup and restore opreration... seems like location service is still llokinf for the old iPhone X device, instead of updating it to his current device list?

I tried everything, from restting his iPhone, disabling / enabling everything related to Location Services, Location Sharing, removing and adding him again from the Famili Sharing group, etc.

Thanks a lot in advance.