Issue Adding External Products To Cart

Hi,
I have a store containing self stocked products in addition to external products, i.e., from Amazon.

https://younyours.com/products-page/amazon/beaba-babycook-duo-limited-edition-bundle/

My issue is that, when viewing these external products in Single Product View and click add to cart, I am redirected, as expected, to the external link, in this case Amazon.

However, in Grid View when I click Add to Cart, it just adds the product to my basket. I have not gone beyond this point yet, however this seems peculiar behavior for a product hosted off site.

Any advice or insights you can offer?
Thanks

Shane

https://www.ads-software.com/plugins/wp-e-commerce/