In this file: templates/shaper_fixter/sppagebuilder/addons/slideshow_full/site.php I have changed the line 39 from this
$bg_image = ($slide_item->bg) ? 'style="background-image: url('/ . JURI::base() . $slide_item->bg . '); background-repeat: no-repeat; background-size: cover; background-position: center center;"' : '';
to this
$bg_image = ($slide_item->bg) ? 'style="background-image: url('/ . JURI::base() . (is_string($slide_item->bg) ? $slide_item->bg : $slide_item->bg->src) . '); background-repeat: no-repeat; background-size: cover; background-position: center center;"' : '';