Grass tool problem


I am trying to learn UE4, I think it is a wonderfull and powerfull tool and thank you all for this great software.
The problem I have is when I follow this tutorial:

And try to setup the texture in the Material Editor it got stuck on this particulair texture:


What should I do to stop this from happening?

(the entire editor got stuck like frozen and it doesn’t give me a clear error message)

Thank you in advanced!

How can I fix this is there a help about this issue? Really want to continue studying UE4?

Still no update on this after 3 months?

After one I gave up on Unreal Engine, no support at all… too sad.

The documentation there is very old (very old), but the editor shouldn’t freeze. What kind of hardware spec do you have?