Is the desired Track set to the right Port?
If you have 'Send All MIDI to DXi synth' (or close) selected, try turning that off.
Point the track Port to correct MIDI output.
Sounds to me like a routing issue during playback.
Then make sure the MIDI Channel data for that track matches what the synth is expecting to receive ..
Or maybe there is a Patch Map for that synth so all the MIDI uses it. Lots of possibilities.
Appears there is indeed a Patch Map for that keyboard here
https://www.pgmusic.com/support_miscellaneous.htm May be worth a shot