Hi,

this button works differently depending on your Odoo db settings. It looks like you haven't activated the multi-locations regime. So, Odoo considers that you have only a single place to put stocks of this product. That's why there is no sense to open the list (actually, the way to choose that is a little bit more complex, but for your question other aspects should not matter).

Thus, go to Inventory > Configuration > Settings. Find here "Storage Locations", and tick its checkbox. As soon as that's done, the button will redirect you to the tree view of stock quants.