Need help connecting guitar in Tonelib Jam

Hi, sorry for my ignorance. I have both Tonelib Jam & GFX. I'm new to this software, so please bear with me.
1. GFX works with guitar great in standalone.
2. I've configured my interface in Options. I have a Blackstar Polar 4 interface & the software is running on my MI Mac-Mini, OSX Tahoe. When htesting the output from my interface in options, I get the 'beep'. Next to Input, I don't get any signal showing.
3. The tuner shows nothing either.
Obviously, I am missing something. Can anyone help? I'd really appreciate it.
Regards
Steve H