Add to cart when logged in, shows as "read more" when logged out?

I have a woocommerce shop set up, but also have pages listing certain products. When I’ve logged in to the site, the Add to Cart buttons show up as they should on these pages and function correctly. But when I’m not logged in to the site (as most first time visitors wouldn’t be) these buttons change to “read more” buttons, and when clicked return a 404 not found page.

Here is the short code I have below each product on the page:
[add_to_cart id =’288′, sku=’EBB11′]

(obviously ‘288’, and ‘EBB11’ apply to a certain product)

Why is this happening?