WordPress at a glance
action is not described

woocommerce_process_shop_order_meta action-hook . WC 1.0

Check the post type.

Usage

add_action( 'woocommerce_process_shop_order_meta', 'action_function_name_5026', 10, 2 );
function action_function_name_5026( $post_id, $post ){
	// action...
}
$post_id
-
$post
-

Where the hook is called

WC_Admin_Meta_Boxes::save_meta_boxes()
woocommerce_process_shop_order_meta
woocommerce/includes/admin/class-wc-admin-meta-boxes.php 220
do_action( 'woocommerce_process_shop_order_meta', $post_id, $post );

Where in WP core the hook is used WooCommerce

woocommerce/includes/admin/class-wc-admin-meta-boxes.php 52
add_action( 'woocommerce_process_shop_order_meta', 'WC_Meta_Box_Order_Items::save', 10 );
woocommerce/includes/admin/class-wc-admin-meta-boxes.php 53
add_action( 'woocommerce_process_shop_order_meta', 'WC_Meta_Box_Order_Downloads::save', 30, 2 );
woocommerce/includes/admin/class-wc-admin-meta-boxes.php 54
add_action( 'woocommerce_process_shop_order_meta', 'WC_Meta_Box_Order_Data::save', 40 );
woocommerce/includes/admin/class-wc-admin-meta-boxes.php 55
add_action( 'woocommerce_process_shop_order_meta', 'WC_Meta_Box_Order_Actions::save', 50, 2 );
woocommerce/includes/tracks/events/class-wc-orders-tracking.php 22
add_action( 'woocommerce_process_shop_order_meta', array( $this, 'track_order_action' ), 51 );