When I set Negative Track Delay on an expression map, the first note of the score does not make a sound (presumably because the sound is supposed to start before the playback has begun). For playback purposes, I can make everything start on the second bar instead of the first, but that is a hacky workaround that shouldn’t need to be done.
Another possibility is to adjust the start of the first note a little to the right manualy in the key editor.
This worked, thank you! For whatever reason, the pre-roll needs to be longer than the negative delay - in my case, the delay is -250ms and I needed to use 0.4s pre-roll, 0.3 did not work. Just saying this in case someone else comes across this thread with the same issue.