Background image of the home page not showing on phones

Hi
I have an issue with the Flatsome theme for Wordpress that I purchased. I built my website with that, but the background image on the home page does not show on phone. It is visible on desktop but not on phones. I checked the option to be visible on all devices but it still not showing on phones. how can I solve that.

Thanks

Hi,

Contact with your purchase item author @UX-themes right here as a comments

Thanks!