I was playing around with some of the less common instruments in GPO 4.0.2 and I found that if I added the Contrabass Clarinet Solo in Finale's Setup wizard the Contrabass showed up as just another Bb Clarinet (not contrabass) with the inherent transposition with of course produces no audible tones, because it is simply too high for the Contrabass to play.

To get around this, I set the staff properties (I'm using Finale 2011) to a staff with the Bass clef 8ma and to transpose that to a treble clef two octaves up and into Bb.

That results in the top playable GPO note displaying as G# an octave above middle C, playing as the F# below middle C.

I am unsure, but this sounds like a problem with GPO, not Finale.