Just saying that the bug pointed out here still exists in the 4.13.2.
I had to move a node, apply and save again the material so that the material is properly displayed while running the game outside the editor.
I tried to delete the intermediate folder to re-build the shaders, without success. Only the previous fix worked.
Here is how I run my game while developing it:
“C:\Program Files (x86)\Epic Games\4.13\Engine\Binaries\Win64\UE4Editor.exe” “ThisNameIsCool.uproject” -game 127.0.0.1 CLIENT1