(The chipset is pretty basic because I've just wanted to practice)
I've tried to set the fuchsia color as transparency and put it in the square the Help center marked, I assumed it would work since I've also used the default chipsets that come with RPG maker as ref but it didn't worked.
This is what it looks in the Lower Layer

But this happens when I edit the upper layer (making my playable character also invisible unless he walks into certain objects)

If someone can explain me how to fix this so transparency work I higly appreciate it! Thanks a lot!
(As you might noticed English is not my first language, you can ask me to reword something, but otherwise i can read english fine so no need to limit youself explaining, also hablo español ^_^;; )