(Bug?) Looping sound sometimes just stops when distance is 0

I want the sound to always play when the distance overlaps the trigger region. At 0:09, the distance is 0, which overlaps the trigger region of the bottom sound, yet the sound stops playing. I don’t understand why.

Are you saying that once distance leaves the trigger region of the bottom sound, that sound will become untriggered, and then, when I move it back into the trigger region it stays untriggered and thus stops? I would expect the sound to become re-triggered when distance overlaps it again.