Plugout issue with System 1m

[Jabbzz]

I am using a MacBook Pro running Catalina, and my System 1m has version 1.30 installed.

I am trying to send the SH-2 plugin to the System 1m, but when I click the plugout button on the software, it says 'Midi communication failed'. I have connected the laptop directly to the System 1m with a usb lead, and the System 1m shows up in the AudioMidi application.

Is there something really obvious I am missing here?

[Jabbzz]

Can anybody help with this? All I ever get is the 'Midi communication failed' error message.