Qsynth not producing sound when used from within frescobaldi

[John Helly]

Aloha.

I'm using FB 2.20.0 with Qsynth 0.5.6 with fluidsynth 2.0.5 on OSX 10.14.6

When I try to playback midi from a score within FB using Qsynth, Qsynth
shows the midi messages and the green-light blinks on and off
appropriately but I get no sound. I've loaded the
GeneralUser_GS_v1.471.sf2 soundfont and cannot find out what's wrong.

At one point this did work but the circumstances were odd.  I was
similarly struggling to get it to work then, out of nowhere, there was
scratchy irregular playback that finally stabilized and worked well. 
However, as I feared, when I tried to restart the setup, I was back to
the same deal: all looks ok but no sound.  This points to something
about the soundfile but I don't know enough to further debug.  Any
thoughts or pointers would be welcome.

When I play the same midi file with fluidsynth from the command-line
with the same soundfile it works fine and SimpleSynth and VLC work fine
so I know the computer audio is ok.

I've tried changing the audio setting from default to speakers but no
joy there either.

Mahalo.
J.

-- 
John Helly, University of California, San Diego / San Diego Supercomputer 
Center / Scripps Institution of Oceanography / 760 840 8660 mobile / 
http://www.sdsc.edu/~hellyj
ORCID ID: orcid.org/0000-0002-3779-0603