Particles rendering as gray squares

I am working through the tutorials and wondering why I’m seeing the particle system “TutorialParticleSystem” as gray squares?

Screenshot: http://i.imgur.com/z2IPq8Q.png

What am I missing?

Yes that happened to my project too. What you can do, is manually add the material inside the same folder. I couldn’t change the material in the editor so I had to change it inside the particle system. However, judging from how it’s inside the Engine folder, I like to duplicate the particle system and keep the original just in case.

How do you add the material to TutorialParticleSystem? I can’t drag it there and I can’t add it by browsering. I can’t add any material to it. It is forever “None”.

As of 4.12 "Fix Up " still isn’t having any affect so Wesysc’s remedy of using Windows Explorer is the only thing that worked for me.