RectMask 2D Child Issue

Hi there!

I'm stucked with a problem in the RectMask. It works properly for the childs making them banish porcentually when they reach the border, but I don't know why the childs of those childs doesn't work.

I will add a video to explain my self better =)

https://gyazo.com/e1c52d5ad53b7275679415e5fe7768b8
As you can see in the image there is one panel with the RectMask2D, a child with the ScrollRect panel, a lot of childs as buttons (the squares) and finally there are one child in each button with the inner image, that one, when it reaches the RectMask2D border, dissappears at once, without a previous splitting.

Does someone know if I'm missing something or how to solve this issue?

Thank you so much, guys!

EDIT: (It happens only with the UI images that have a Material. I need it to apply Font Material to turn them white). Is there any other option or any solution?