I found Storyline's shrink ray
I've noticed some weird stuff happening when I try to use illustrated characters and make portions of them transparent.
The first one I tried (attached) was a character holding a poster. When I made the poster transparent, it shrank the character (you can see it if you preview or publish the file).
The same thing happens with other poses (e.g. "one hand hip" with the shirt transparent).
Interestingly, it doesn't happen with the included photographic character ("Atsumi").