Material is not showing

Love the graphics in new UE 4.11!
But when dragging material to any object, it is not visible… Instead it shows pattern of squares as if material is missing…
( in UE 4.10 all worked fine)
Anybody has an idea why this is happening? Do I need to somehow pre-render the materials maybe?

Thanks for help!

How does the material look in material editor? Is it giving any errors?

It looks as if it is loading, but it never loads…
And the messenger says ‘a new material is created’