Triggers not working with scrolling panels, such as "When Object enter slide" and "When Object intersect"

I'm trying to create a similar interaction. I want relevant images to appear when the user scrolls to a certain point in the scrolling panel. I quickly discovered that the 'when object leaves slide' event doesn't do what I want. I also tried to use the 'when object intersects target' event, by having an object embedded in the scroll panel trigger a layer when it intersected a stationary object on the base slide. I had high hopes for this, but Storyline refused to even preview the slide when this trigger was turned on - all I got was a blank white screen.

It looks like there is no way to get this kind of interaction to happen with a scrolling panel?