And when you press "play" the MIDI is played by Sound Center with the sounds of your choice,
but when you select both of the tracks (Tracks,
not clips), MIDI and audio, and bounce or export, you only get a silent flat line? Or, if you select nothing, it's the same as selecting all (if there only is this one soft synth track.)
And the output of the MIDI track is Sound Center, and the input of the audio track is Sound Center?
Or, if you use simple instrument track, you click on the track number to select both MIDI and audio, and get a flat line all the same?