Hi,
The problem is that you have deactivated the "link to product pages" option of your listing so the image/name is not clickable. So the $link variable is not used.
And only the add to cart button is displayed. And since your products have variants, instead of the add to cart button, you have the choose options button displayed which has his own link.
So you need to go edit the file "quantity" of the view "product" via the menu Display->Views and change the line:
echo $this->cart->displayButton(JText::_('CHOOSE_OPTIONS'),'choose_options',$this->params,hikashop_completeLink('product&task=show&product_id='.$this->row->product_id.$this->itemid),'window.location = \''.str_replace("'","\'",hikashop_completeLink('product&task=show&product_id='.$this->row->product_id.$this->itemid)).'\';return false;','');
to:
echo $this->cart->displayButton(JText::_('CHOOSE_OPTIONS'),'choose_options',$this->params,hikashop_completeLink('product&task=show&product_id='.$this->row->product_id.'&Itemid=XXX'),'window.location = \''.str_replace("'","\'",hikashop_completeLink('product&task=show&product_id='.$this->row->product_id.$this->itemid)).'\';return false;','');
Then it will work for the choose options button too.