I have also encountered this bug. When first loading and playing a song with the new synthesizer instrument in it, the synthesizer behaves exactly as if it is fully muted, either by volume slider or the mute button in the advanced tab.
Further info:
This is NOT fixed by entering edit mode BEFORE starting the sequence for the first time; sequence MUST be started once, then paused and REstared before the synth.
-This is independent of whether you start the sequence with the play button overlay, the play button in the upper left, or if you enter edit mode and click somewhere on the measure counter bar.
This is NOT fixed by letting the sequence loop; synthesizer continues to behave as if muted on each subsequent loop.
This is NOT fixed by using a marker to directly set the instument volume attributes. I have tested this with a marker manually setting EVERY attribute (except instument reset), and none of them resolve the mute issue.
This IS fixed by using an instument reset marker prior to reaching the synthesizer.
Personal suspicion: somehow the sequence is being initialized with the synthesizer's mute active, and this is only rechecked if the sequence is restarted.
