Hi Kristine, please allow me to step in. Can you please confirm you created your project/metric in the Pixel Perfect user interface? Please note that Element masking is available only in the Pixel-perfect interface (Enterprise Customers). In Analytical Designer, element masking is not supported. If you created it in the Pixel Perfect UI, feel free to check our
documentation on this topic and let us know on which step are you stuck or if you need further help 🙂