@megan when you use the preview animation button, Composer doesn’t care about the trigger, it just tries do play the animation.
@trenken311 I just did a similar action on my side, having an image within a group, and the animation plays well
I’d recommend you to contact our support team and share your XP with them so they can have a look at it.
My original question about the group was to see if the image isn’t clipped by the group boundaries, which would prevent you from seeing this animation until the image is maybe first moved in a visible area.