Hey, I dont think this is an intended feature and it seems to be doing it on its own now that I've done it a couple of times on accident. When holding shift like you are about to select buildings and change floors, all the platforms and everything on it disappear but reappear when zoomed out. If you zoom back in, the platforms disappear again. The only way to fix it is by holding shift and changing floors again.
What i expected to happen was just to change floor levels so i can select other buildings on the platform.
Here is video of it happening.