Hi,
I suppose that you must have add the code:
$this->setLayout('show_block_tags');
echo $this->loadTemplate();
in the view file product / listing_img_title via the menu Display>Views to get that result.
And that's normal because the "show_block_tags" view file you're calling expect the product data to be in $this->element->main (which is the case on the product details page, while on the listing the data of the product is in $this->row.
What this means is that if you want this to work, you need to add this code before the code you added:
$this->element->main = $this->row;