Why does Platform Trim not work on Platforms?

I've been looking around everywhere on how to fix this bug. I just started to use platforms in build mode, when I tried to change its color using the platform trims, it wouldn't change. I would get a red error box if I touched the side to change it saying, "No changes to be made". If I try to do the same thing but from the top view, I get another red error box saying, "Must be applied to a room". I tried using half wall trims as well, as wallpaper and flooring. Only the flooring will apply to the platforms. I don't have any cc downloaded, and the Sims 4 packs I have downloaded are; Cats & Dogs, Paranormal, Tiny Living, Laundry Day, Toddler, Fitness, Vintage Glamour, Romantic Garden, and Perfect Patio. We've downloaded most of this since January of this year. I have not previously tried using platforms in build mode, and was unaware of this issue until recently. Another bug with platforms is that I cannot attach stars to it to allow my sims to get in and out of the house. Is there any fix to this issue with Platforms?