Perhaps this is the OP's problem: when inserting a soft synth, if I don't select "simple instrument track" I don't get sound. I can see the MIDI activity but no sound.
If I go to "inspector" I see the out going to the soft synth but I don't see where the soft synth is routed (ie Master).
I always just select "simple instrument track" but I wonder if this is what the OP is seeing.
I've never bothered to investigate further as to why I can't find where it's routed so maybe this is the time.
Thanks very much,
Randy