Why is my thumbnail preview in the Material Editor not displaying my resulted material? I can open other (existing) materials, and their preview displays fine. But ones that I make aren' t!

I’m having an issue regarding my thumbnail preview in the Material Editor. I am trying to make my first Landscape Layer Blend, but I can’t see my changes (or what it looks like) in the preview sphere located in the upper-left hand corner of the screen.
I can apply my newly-created material to my landscape; I just can’t view the thumbnail (preview) when I should be able to!
Someone please help! :face_holding_back_tears:

                                                                     Justin

Hello Parabellumx8086, welcome to the Unreal community.

This is quite common as this occurs when materials have blends. There isn’t an error with your material from what I can tell.

Here is a brilliant answer posted by RecourseDesign

I hope this helps.