how to stop pattern from looping in a performance

I'm using a pattern as a part in one of my performances. This pattern when played alone does a short pulsating thing, then stops and holds the note for as long as you hold it down.

For some reason, when I use this same pattern in my performance, it continuously loops the pulsating part when I hold the note down. I can't find any paramater to make this stop. Any ideas?

Thanks!