Webflow renames form fields when you paste them; each field's Name must match a key of the metaobject definition exactly.
The symptom. A metaobject creator form sends, but the entry in Shopify is missing fields, or is not created.
Why. Each field’s Name, in its element settings, is the key of a field in Shopify. When you copy and paste a form, Webflow can rename its fields, and a Name that differs by one character saves nothing, without an error.
The fix. After pasting, open each field and check its Name against the definition’s keys, under Settings › Custom data › Metaobjects in Shopify. Names that start with _ are never sent: use them for fields that only help the visitor.