Landscape missing texture in-game but not in PIE?

Did anyone else encounter this bug? It just shows the purple missing texture no matter what. It’s fine only when previewing or playing through the editor.
UDK version is July 2013.

The fix was to copy the material to my own package, and use that.

I have this issue but do not understand your solution. It is very vague. Could you please add more detail.

start PIE, close it, save the package that the material is at, cook and try again

The material was in one of the stock packages, I copied the material to one of my own packages and made the landscape use the copy of the material as the landscape material.