WooCommerce was updated to version 2.2.6, from version 2.2.5. Changelog:

• Fix – Notices in the cache helper.
• Fix – Prevent bulk edit from breaking sale price scheduled dates.
• Fix – Prevent address fields being empty when editing an address within an order.
• Fix – Removed save_post remove_action call which breaks 3rd party plugins. See ticket #6376 and #6485 for details.
• Tweak – Added woocommerce_product_subcategories_hide_empty filter.
• Tweak – Added filter for shipping tax.
• Tweak – Product attribute shortcode should return columns css class.