If your size chart is assigned to a Shopify collection but doesn't appear on some products in that collection, the collection may be using Shopify's exclude filter — a condition that prevents certain products from being included in the collection.
Kiwi uses Shopify's collection membership to match products to size charts. When a collection uses an exclude condition, Shopify doesn't fully expose that membership to apps, so Kiwi can't reliably tell which products belong to it. The result: the size chart shows on some products but not others, even though the collection looks correct inside Shopify.
How to tell if this is the problem
Open your Shopify collection settings and look at the conditions. If any condition reads "is not", "does not contain", or "excludes" — for example, "Product tag is not Sale" or "Vendor is not Discontinued" — that's an exclude filter.
The fix
Create a new collection (or update your matching conditions in Kiwi) that only uses inclusive conditions — no exclude filters.
You have two options:
Create a new Shopify collection using only positive conditions (e.g. "Product tag is X" instead of "Product tag is not Y") and assign your size chart to that collection instead.
Switch the size chart's matching condition in Kiwi from collection-based to tag, product type, or vendor-based. These condition types don't rely on collection membership and are not affected by Shopify's exclude filter.
Either approach will restore consistent chart visibility across all intended products.
Why not just edit the existing collection?
Removing the exclude filter from your Shopify collection changes which products are in it, which may affect other parts of your store (navigation, discounts, etc.). Creating a separate collection for Kiwi matching — with only inclusive conditions — keeps your existing collection intact.