Hi JP,
This appears to be something that was missed as I believe the intention was to have the same materials available for each field. I’ll take this back to the dev team for further discussion.
In the meantime, I would recommend doing the following:
- Draw a wall in the model with the desired material.
- Go to the Materials section of the Default Tray & click on the Home icon. This should show a list of all materials in the model.
- Locate the desired material from the list. If you use the Sample Paint feature (eye dropper icon) it should select the material for you.
- Right-click on material & select Export Texture Image. Save the image somewhere on you computer (the desktop is usually the quickest & easiest).
- Open the Hip Roof Tool & go to the Gable/Dutch Gable material field.
- Click on the Create/Manage & follow the steps to create a new material.
After complete the above steps the same material should then appear in the material field. Note: Prices & other takeoff features will need to be hooked up for each instance of the material.
If you’re using PlusDesignBuild, another option would be to use the 
Custom Estimation Tool to apply the material to the gable face.