Theme's Slider Background Not Working with New Version (4.1.1)

I’m using the FIAT LUX theme, and I cannot get the background slider to work: https://www.ashevillefashionweekusa.com

It works on my other WordPress site, which is running version 3.8.5: https://www.knoxvillefashionweek.com (this theme also has a child theme). I’d prefer not to have to downgrade to get the background slider to work.

This is a newer website, so when I added it to WordPress it was already running 4.1.1. I have not upgraded it since installing the theme. The slider has never worked.

The settings are entered correctly. The images are properly uploaded and linked. I double checked everything against the site that is working.

I cannot find any sort of support forum for the FIAT LUX theme specifically on the theme’s site.

Does anyone have a possible solution to this? Or something I might try? I’d really like to get the slider background working.