Zoom to center of stage?

Hi friends

I'm working on an exploration-style slide, and am struggling with getting the zoom effect I want (screenshot enclosed): When I click on one of the seven objects, it grows/zooms into the center of the stage, where I can run some text and speak (in a layer or a separate slide).

I've tried this:

1. The built-in Image zoom doesn't center the image on the stage, and this can even violate the player borders (see screenshot). If this could center the zoomed image onto the stage, it would be perfect.
2. Zoom region zooms and pans the entire stage, where I want just the selected object to grow and cover the others.
3. Using States I can get the centered/resize position that I want, but no animated zoom effect.

The third option is closest to what I want. I found it described here:

https://community.articulate.com/articles/how-to-create-your-own-zoom-picture-effect-in-articulate-storyline

Initially, I interpreted this as having a Grow-style animation effect from Normal to Selected, but that's not the case: I just get a magnified version of the original when selecting the image. Adding Animations to the States is not an option, animations are greyed out when I Edit States. All options considered, this is the best, but not quite what I'm looking for.

Any ideas/suggestions?