Set Paper2D Layer Alpha?

Hi there…

I tried to create a Tilemap, that has various Layers. Now, when the player Sprite walks behind a wall, i ant the “Roof” layer to get invisible.

Via Blueprint, i can get the reference to the current Tilemap, get the Layers and get the Roof layer out of the Layer Array.
But, there seems no option to change its alpha or visibility?

Any suggestions how to archive that without the use of a second tilemap for that layer?