Background image appearance in Graceful theme

I’m new to all this, I am employing the Graceful theme on an embryonic discourse implementation.
In the theme setting there is an option for a background image which has a default. I wish to change this.
If I upload an image and set the image variable to an uploaded image, it will not display. I have tried it with .jpg and .png, small images, large images but no dice.

Am I being dense here or in order for this to work do I need to set export the theme and set up my own repo on GitHub for it to work?


I ended up just using the uploaded image URL, that worked fine…


That’s a good workaround for now, I’ll take a closer look when I have time - but it seems like using a variable broke at some point.