Before a product can go to Amazon, two fields must be filled in on the Shopify side: the product's Brand (vendor) and its Description. Until both are saved, the app will not let you select the product on the Product Sync list, and the product detail page stays locked.
This is deliberate, and it is one of the few places where the app is strict rather than helpful.
Amazon rejects listings that arrive without a brand and without a description. If the app let the push through anyway, you would get a submission that failed several minutes later, an Issues badge, and no listing. Blocking early is a shorter path to a working listing than letting you push and then explaining the rejection.
The other reason is that Shopify stays the single source of truth. Your Shopify product page is where the content lives. Filling these fields in Shopify means they are correct everywhere: on your storefront, on Amazon, and in any future marketplace you add.
On the Product Sync list, a product missing either field shows a Required fields missing state. Its tick box is disabled, so it cannot be included in Push selected or Sync all, and the push action is replaced by a Set required fields button that takes you to the product.
On the product detail page, a banner at the top names exactly which fields are still missing. While that banner is showing, the page is hard-locked:
Only the Shopify column and Save to Shopify stay active. That is intentional: the page gives you exactly one thing you can do, which is the thing that unblocks everything else. Hovering a disabled control shows a tooltip explaining that the required Shopify fields must be saved first.
You have two routes, and both write to the same place.
Open the product in your Shopify admin. Set the Vendor field, which is what Amazon calls the brand, and write a product Description. Save. Return to the app and refresh the product.
You do not have to leave the app. On the product detail page, the attribute table's Shopify column is editable for these fields. Type the brand and the description there, then click Save to Shopify. The app writes the values back into your Shopify product, exactly as if you had typed them in the Shopify admin. The lock lifts and the AI tools, Apply and save and Push all become available.
Note
Save to Shopify is not the same as Apply and save. Save to Shopify changes your actual Shopify product. Apply and save stores an Amazon-only override that does not touch Shopify. See Reviewing a product.
Tip
The brand you put in Vendor should be the real brand name of the product, not your shop name, unless you genuinely are the brand. Amazon compares it against its brand registry, and a mismatched brand is a common source of listing errors.
Brand and Description are the app's gate. Amazon has a second, larger set of requirements that depends on the product type you mapped for the category. See Amazon product types.
Once a product type is set, the app fetches Amazon's schema for that type and checks your product data against it. If Amazon insists on an attribute that nothing in your Shopify data supplies, you will see a warning like:
{n}required attribute(s) missing
and, when you attempt a push:
Missing required attributes:
{fields}. Provide them via Shopify data or Field mapping (Product Sync settings).
The list of missing attributes is shown against the product, so you can see exactly what Amazon wants. These are things like a material, a colour, a size, a department, a part number or an item type keyword, and which ones apply depends entirely on the product type and the marketplace.
There are three practical ways to satisfy a missing required attribute.
custom.material, or a Static value. A static value is the fastest fix when the answer is the same for every product in the category, for instance a department of "unisex-adult".Field mapping is usually the right answer, because it fixes the attribute for your whole catalogue rather than one product at a time.