Qsynth with OSX Sequoia via MacPorts

Aloha.
I've had to re-install MacPorts to get lilypond, frescobaldi, and qsynth. They all work except qsynth doesn't produce any sound. I've run qsynth with frescobaldi successfully previously but not on this configuration.
The system is :
Mac Studio M2 chip
OSX 15.1 Sequoia
I've configured the MIDI interace on frescobaldi such that I successfully see MIDI messages going to Qsynth and the light blinks green each time. I've got soundfonts loaded and have tried switching them with no difference.
I've tested the sound using Logic Pro and Apple Music. A USB midi keyboard works with Logic Pro but Qsynth does not see it. This may be a separate problem.
I'm seeking advice on debugging this as I can't tell if it's a configuration issue that I'm screwing up or some other kind of OS-related problem.
Any advice would be welcome.
Mahalo.