Issues with piccolo playback- ignoring accidental

I am writing a piece for wind ensemble that involves the flute and piccolo doubling in octaves, and there is one point in the melody where the piccolo decides that it doesn't need to play the G flat I've written. It's in the key of Eb mixolydian so a 4 flat key signature. It wouldn't let me attach a video but it does it only when in that one octave. I tried putting just the G flat on its own in the same octave and it worked. however it does not change the playback regardless of if it's slurred or tied, or regardless of what voice it is in. This is really annoying because I want a good playback I can share with the band I am giving this to and I don't want to sacrifice what I write for the sake of the playback.