I understand, the variables could be many, maybe even just a Joomla cache problem that you haven't cleaned up.
It all also depends on how you are using the addon, maybe, unlike me, are you using the background function?
You should see the specific site to understand what is not working, I use the template on two different websites, I have made that variation in articles_layout and articles_thumb_slider and it works correctly in both.
However, I notice that in my variation the row does not correspond to yours, I would not like you to have replaced the variable only with the previous IF and not the next one:
if(($articles_layout === "liberica" && $key === 0) || ($articles_layout === "bourbon") || (($articles_layout === "java") && $key === 5) || (($articles_layout === "robusta") && $robusta_classic && ($key === 0))){
if(isset($item->image_thumbnail) && $item->image_thumbnail) { /* personalizzazione */
$output .= '<div class="bg-img-wrapper" style="background-image: url('/ . Uri::base() . $item->image_thumbnail . ');"></div>';
}
} else{ /* personalizzazione */
if(isset($item->image_thumbnail) &&$item->image_thumbnail) {
$output .= '<a class="sppb-article-img-wrap" href="'. $item->link .'" itemprop="url"><img class="sppb-img-responsive" src="'. $item->image_thumbnail .'" alt="'. $item->title .'" itemprop="thumbnailUrl"></a>';
}
}