Although OctaneRender will render Unreal materials natively, Octane materials render in the Octane Viewport, but not in the Unreal viewport. In this case, the Parent MaterialThe representation of the surface or volume properties of an object. node will control material characteristics in the Unreal viewport while Octane materials will control the material characteristics in the Octane viewport.
Figure 1: An OctaneRender-specific material applied to the table statue (right) will render in the Octane Viewport while the Unreal material is visible in the Unreal viewport (left)