I set a body background image on a site with GeneratePress and the Polylang plugin. The image is visible in the Dutch and German version, but not in the English version (see attached url). I cannot tell whether it is the plugin that causes it, because disabling it obviously breaks the site.
The background image URL looks broken. If you right click the body and “Inspect”, you’ll see the URL in the CSS. If you try to open that URL, you’ll see it doesn’t go anywhere. Can you make sure the image uploaded correctly?