drumline bug 9/4/20

I've been working on a drumline cadence, and whenever I pause it (suddenly?) it sometimes has a chance to play ALL of the notes at once by my guess (hard to tell, but it seems the more notes I've put in, the louder it is), and then when I play the song, it completely messes up the rhythms, and I have to restart the whole program to fix the playback. I'm on Mac, and I used MDL snare line, MDL tenor line, MDL bass line 5, and old cymbals if that matters.