"Find My" reports the person to always be at home

When using Find My, it is always reporting one of my family as being at home, regardless of his (and his iPhone's) actual location

He only has one apple device (an iPhone SE), which is has "Find My iPhone" set to On, with "My Location" as this device.

"Find My" always reports the location of his iPhone correctly. Some how "his" location has become detached from his phone's location.

I have tried deactivating "Find My" on his iPhone, restarting it and then reenabling it, to no avail.

There are no problems with any other family members, including those with the same phone model.

Any suggestions as to how to resolve this would be very gratefully received.