TikTok inherits the Google Product Category taxonomy in catalogs. If this field is blank, the product is downgraded in diagnostics and may be skipped from delivery.
TikTok Shop / TikTok Catalog Manager's product schema has format and value rules per attribute. This issue is typically: missing a required attribute for the category, an invalid enum value (e.g., 'XL' submitted where 'M, L, XL' is the valid set), out-of-range numbers, or attributes that conflict across the feed.