The dance floor is made entirely of surface guis, and you cannot see most of the particles (which spawn equally on the entire surface) or even see the transparent objects.
Where is the center of the dance floor located, and is it a single part?
Seems like the center of the dance floor is closer to the camera plane, which makes the surface GUI render in front of the semi-transparent character. These sorting issues for transparent parts are known issues (if that’s what’s happening here, at least).
Every part you see is an individual part (they flash in patterns and what not), so what you’re saying is probably true.
I’ve searched a bit and it seems like this problem dates back to as far as 2013:
I found this discussing the same set of bugs: