I have the two common Dxi synths: Forte and Coyote WT.
Right now, I have the Coyote Dxi at Port 17, and the Forte Dxi is at port 32 (the Default Position).
Output driver setup: GS Wavetable, Re-Route Midi playback is checked, Forte Dxi is in default position.
I also have a little four-track Midi file, all BB tracks:

I start the midi file playing - I get no sound - I go to the Port selection window, and I click on which-ever Dxi synth is not shown in the tracks windows WHILE THE SONG IS PLAYING - I get sound, and I can spread it to all tracks. I stop the play and re-start the song - again, No Sound - until I once again go to the Port selection window and select the opposite Dxi synth WHILE THE SONG IS PLAYING.

It seems that the only way I can "Kick-Off" the Dxi synths is to invoke them While The Song is Playing.
Has anyone seen this before?