MacBook does not appear online in Find My Phone

In setting up a new iPhone SE, I noticed that in Find My Phone, my MacBook Air appears with my other devices, but not online. So Find My Phone cannot find it, should that become necessary.

The MacBook Air does appear in Account Settings, complete with serial number, with all the other devices.

I believe I have enabled Find My Phone in Privacy & Security on the MacBook Air, so

why is Find My Phone not working with the MacBook Air?