Unfortunately, adding the !important code doesn’t help. Is this something to do with the Upper and Lower layers having a different reference code in the CSS than just “background-attachment:”? It seems as though just referencing the background wouldn’t tell it which layer background to look at to apply the code. The practical thing would be to have another option on the setup tab for that section under the corresponding layers to where you can select from a dropdown for the different options for a background-attachment, seeing as how you did this for the background-position and background-size settings.
I appreciate you guys adding so many features to the front end Cornerstone builder, but it seems the customization on the backend is suffering a bit with this update.