Hi,
If you look at the code in the view listing_img_title which is used for the listing of products by default you can see that:
$img = $this->image->getThumbnail(@$this->row->file_path, array('width' => $this->image->main_thumbnail_x, 'height' => $this->image->main_thumbnail_y), $image_options);
if($img->success) {
echo '<img class="hikashop_product_listing_image" title="'.$this->escape(@$this->row->file_description).'" alt="'.$this->escape(@$this->row->file_name).'" src="'.$img->url.'"/>';
}
So if the call to getThumbnail would return nothing, it wouldn't go in the if and the img tag wouldn't be displayed at all.
I've checked your website and I can see that the view was heavily modified:
take.ms/PfJap
And I actually don't see the img tag, just an a tag without any img tag inside (I suppose that there should be the img tag normally in there).
I would say that there is a high chance that it comes from the customizations in the view files.
If you rename the folder templates/YOUR_TEMPLATE/html/com_hikashop/product/ to something else via FTP, that will deactivate all the overrides for the products. If the images are then displayed properly, they it would confirm that it comes from the modifications of the code.
Otherwise, it might be an issue with the generation of the thumbnails (like not being able to store the thumbnails after their generation due to a permission issue in your upload folder or something similar).