AirTag is showing at home, when it’s not

An AirTag relies on Bluetooth and the Apple Find My Network to work properly. The latter, as you may well know, consists of literally millions of iPhones.

Keeping the technical jargon down to a minimum, the tag transmits a Bluetooth signal, with its ID, approximately every 3-5 minutes. Any iPhone, properly configured and within Bluetooth range (~30-40') of it, can receive this signal. If that phone also has an active Internet connection, it can then relay the tag's ID, along with the phone's GPS location, to the Apple servers over that Internet connection. This is where you would see an updated location on the Find My app on your iPhone.

As you can see, a number of things need to "fall in place" to get those updates. When they don't ... well, you don't get consistent updates.

It's about a brief explanation of how an AirTag works, and the potential reason that you are not seeing any location updates.

Just because he has an iPhone with him, doesn't mean that his phone is relaying the tag's ID to the Apple servers. It should, but in reality, it isn't always the case.

Alternately, it could just be that this one tag is defective.