Auto-Patch Leaving Faint Outline?

I’ve just been getting to grips with the auto-path node in Toon boom Harmony and have come across a issue that’s left me stumped and wondered if there’s a solution. Whenever I use the auto-patch node and intersect two of even the most basic shapes, it leaves a faint line of the shape below that is only available when viewing through the render view. What’s happening here? Any help would be greatly appreciated.

Auto-patch isn’t too accurate. Try this:

The Auto Patch Node is used mainly when creating joint patches.
Drawn with the Pencil Tool on the Line Art Layer and fill colours on the Colour Art layer.

Thank you, both of these approaches worked and removed the faint outline. Thank you!