exporting leaves an instrument out of the recording

i have a 20-part score for symphony orchestra, with an added synthesizer part. i have installed the aegian symphony orchestra and timbres of heaven soundfont packs, and have saved them to the score. i was previously having corruption issues with the score, but i fixed them so the score does not corrupt anymore.

when i export the score as an audio file, either .mp3 or .wav, it exports just as it should, except the synth part (using a sinewave soundfont) does not export (as in, the piece playbackss without the synth part). i was previously using the '1kHz test' soundfont for the synth, and it did not export the sound of the synth part either.

i have provided a sample score for you to try. (make sure to have the aegian symphony orchestra and timbres of heaven soundfonts enabled.) and, if your score exports everything properly, please send it to me)