The WooCommerce built-in integration in Schema Premium core plugin is not complete 100%, hence it isn’t going to validate the whole Product markup.
Schema Premium itself is NOT 100% compatible with WooCommerce.
Some schema.org properties fields will be missing – can’t be mapped– because of the way Product data is stored in database.
Schema WooCommerce extension
We’ve released the Schema WooCommerce extension to fully integrates with WooCommerce plugin, and insure your product pages have a valid structured data markup.
This solution makes it easier for Schema Premium users to work with WooCommerce, have a valid markup, and remove unwanted markup duplicates.
Using WooCommerce? We highly recommend you install Schema for WooCommerce.