Atari 800 and Picade joystick

I can’t get the Picade joystick to work with the lr_atari800 emulator. I’ve read the docs and know you need to bind the port (1?) to Atari Joystick but no joy.
I can get it to work if I use an external controller - DS4 over Bluetooth - but want to have the picade joystick working.
I’ve read other posts and see that it’s a tricky issue but nowhere can I see the answer?

And somewhat strangely - the Picade joystick DOES work fine if I have the external controller attached. It won’t work if not?