Find My People vs Devices

I can see my son's iphone and ipad devices in the Find My --> Devices tab, however, I can't see him in the Find My --> People tab. All I see is his name with a No location found message under it. When I choose his ipad to be the Use This iPad as My Location, then I see him immediately in the People tab. All sharings are enabled, loacation services enabled, contacts added for all of us, but nothing seems to work. All devices updated to latest ios.

Thanks!