Amazon Fire Sticks not connecting to Ubiquiti Unifi Access Points - Fixed

I recently got fed up with the occasional issue with my Mikrotik Access Point so I purchased a Unifi UAP-AC-LR to replace it. I took the opportunity to change the SSID and PSK as I've been meaning to do it for several years, so I went around the house reconfiguring various devices. I got as far as my Amazon Fire Stick and although it could see the network, it would fail when attempting to connect.

Fortunately I was able to find a solution.