UMG TileView zOrder bug when wrapped by border backgroundcolor

I hope you can give me a hint. I tried to turn off/toggle/unset/whatever many different options but I just don’t get if this is an error, or if I made something wrong bla bla you know.

Placed a TileView inside a Border element to represent selected RTS units.
As long as this list is directly placed on screen it works as Expected (see picture 1). But if the parent of the TileView is a border element with tint/brush with “draw as image/box” the TileView disapears (gets invisible/not drawn) (picture 2).

Added another image: If the border is not fully opaque the child element is visible