I have PSO 4.1.4 and it shows up everytime on a few events, I can only presume I have copied an audio part which previously was used to detect chords with its events. For some reason PSO thinks we want this on new event content and 'remembers' it is/was on.
Resolution: select the audio part and bounce it to one event (CTRL B). The naughty audio part will be dissolved.
Cheers Brett