Actually that number should probably be increased to 18:
"North Dakota Republicans selected 25 national delegates and, of those, 18 were on a list of preferred delegates that Cruz circulated -- a clear win for the Texas senator."
They may not be "bound", but they are Cruz delegates nonetheless...
They may or many not be for Cruz, which might be why the official GOP chart has a different count.
Trump won the straw poll here in ND.