Hi There,
Thanks of writing in.
I believe that you are tying to parallax the whole background of homepage. In X theme or conerstone, you could only parallax a background of a certain section
However, you could follow the link below on how to parallax a background image of a page.
https://community.theme.co/forums/topic/parallax-effect-homepage-background-image/
Hope it helps.
Let us know how it goes.
Thanks.