Today, WooCommerce version 3.5.6 has been released. It has an update for schema.org markup output on Product categories.
WooCommerce used to output limited structured data on Product categories per to Google Guidelines. However, this has been changed in 3.5.6 update.
Structured data is no longer output on archives as it contradicts Google guidelines.WooCommerce
It seems that WooCommerce team didn’t see a use of markup on Product categories and archives, so they’ve removed it from the plugin.
Mostly; here in Schema.Press, we will keep things they way they are since Schema Premium does markup in a different way, the markup output contains a list of items for multiple items on a page (products in this case), but it’s not really a Product markup.
Also, our Schema WooCommerce extension should keep working with no issues regarding WooCommerce update.