Try the following experiment. Load some instrument with sustained tones, like an organ. Clear any existing Script and then enter this simple 3-line script:
play_note ($EVENT_NOTE - 12,$EVENT_VELOCITY,0.-1)
Click 'Apply' and try it.
This simple script simply doubles any key you hit with the same pitch an octave lower. The created octave should last until you release the key that caused it.
Now, here's the problem. Take a finger and sweep it back and forth across your keyboard, playing rapid glissandos. After a few swipes, notes will begin to get stuck on.
This of course shouldn't happen.
I think we've got trouble right here in River City!