Firefox creates seams along the Tile lines if a Stamp is made large enough, has Custom Shadow, and has any changes made to Advanced Color Settings. h Steps to reproduce Select the Stamp Tool and open the catalog Select a Stamp with Custom Shadow (Dead Trees work well for this) Open the Advanced Settings and change a Color value (like Hue) Place a Stamp Increase Size so the Stamp covers most of the canvas HD Export Expected : The Stamp should render as it is in the scene. Actual : The Stamp's shadow doesn't render over the Tile lines properly.