In amongst trying to test Alpha and Beta SO, Raspberry Pi OS and Ubuntus LTS and 23.10, RPi 4 and RPi 5 servers, and RPi 3 and RPi 4 clients, I got my SD cards muddled up.
What I thought was a fully functioning RPi 3 client machine running Alpha 2, was in fact, running SO 1.2.X, not 1.3. I discovered this when I went to upgrade from Alpha to Beta.
Now upgraded, I cannot get the HAT to work. I don't have time to chase down precisely what is happening until the weekend.
Sorry for the muddle and and failing to notice I wasn't running 1.3.