my macbook air will not recognise any bluetooth connections

What devices? You cannot connect Macs and iPhones/iPads directly via Bluetooth (though other connection methods like Universal Control and iPhone Mirroring do use Bluetooth). Other iDevices will NOT show up in the Bluetooth settings on your Mac, that's normal and expected.

What are you trying to pair it with?

You can NOT pair it with an iPhone or iPad. That has never been supported and isn't required for features like continuity and handoff.

What did Logitech say when you reported the problem to them?