Invisible material on mobile, but present from the editor.

[Kymlands]

Hello,
Simple problem. The material used for the HUD "background button" is visible during ingame session from the editor, but invisible once I'm playing the game from my device "Nexus".
Can you give me an hint about what could explain this gap? Thank you.

[Kymlands]

Ok, everything works fine by directly using Textures and not Materials.
I guess that the Materials are not supported into the HUD on mobile devices?