Double check you don't have 'Face' in the Preferences->Surfaces Material Filter. If you can provide a simple scene which reproduces this problem, I will take a look.There is a bug in all the version (2018.1, V4, V3). If an wearable object (shoes / clothing) has a surface named 'Face' and the wearable object is fitted to the character, the plugin does not show the surface name 'Face' under the Materials Tab for that wearable object. You cannot set any materials for it as the surface is not recoganized. I had faced this earlier but never could figure out why the material would not set on that surface. Today I noticed that the 'Face' surface itself was not being shown in the Octane Material Tab. Clicking on the surface in Octane Viewport to edit it in NGE actually loaded the 'Face' material of the character in the NGE.