Hi,
I see that when you use the filter, you get redirected to the page /index.php?option=com_hikashop&ctrl=product&task=listing&Itemid=1695 since you entered 1695 as the "menu" option of your filter module.
This means that you want the system to search among the products normally listed in that menu item.
But if you look at that page without any filter, you get only one product listed:
monosnap.com/file/4YBwZ542oUzQFVluDTz5JG2efyIkpo
This means that you configured your search to only search on that list of product and thus, the filter will only display a result if you use the code TS3320.
If you want the search to happen on all your products, you should edit your menu item with the id 1695 and configure it to display all your products.