[REST API] Order status change hook fires too soon

[neonics]

When updating an order with a status change via the REST API, the new order information is not stored until after the status has changed, causing old order data to be used in the status change hooks.

Example

When an order is shipped, I'm updating the order via REST with the new completed status and the tracking information as metadata fields.

• First $order->update_status() is called, which invokes the status change hooks that send the customer-completed-order.php email.
• In a plugin I have installed a filter for woocommerce_email_order_meta_fields that adds the tracking info meta fields so they appear in the order complete email. Unfortunately these metadata values are not present so they don't appear in the email.
• Only after the order status is updated and the email is sent, is all the other order data actually updated.
  When I then re-send the email via the Edit Order page, the tracking information is displayed correctly.

Workaround

For now it seems that changing the order status must be done separately from any other changes. This means two REST calls per order instead of one.

Thanks again for your time!