[Closed] WPML and order processing hook

Background of the issue:
I have a custom script which triggers with the hook woocommerce_order_status_processing in theme function file, when the order status is changed to processing. I noticed that order meta data is not saved to the database. A deeper investigation showed that the meta is stored but something deletes it, as add_post_meta returns the meta ID and if I look into the database, there is no such ID. I added die() right after add meta, then everything is okay. Even if I read the meta by ID with get_metadata_by_mid(), it returns the meta. But some other process interrupts and deletes my meta. Then I deactivated plugin by plugin and tested them. After disabling 'WPML Multilingual CMS', the meta is stored and stays in the DB. Site credentials are added into ticket #15899109.

Also i made little script which changes the order status so i can fast check when it works and when not.
I tried with order 415612

$order_id = 415612;
$order = wc_get_order( $order_id );
$order->update_status('wc-pending');
echo "Status: " . $order->get_status() ."";
echo "invoice_id_test: " . get_post_meta($order_id, 'invoice_id_test', true);

$order->update_status('wc-processing');
echo "Status: " . $order->get_status();
echo "invoice_id_test: " . get_post_meta($order_id, 'invoice_id_test', true);

Symptoms:
Order meta data is not saved to the database when the order status is changed to processing. The meta data is deleted by some process, which is identified to be related to the 'WPML Multilingual CMS' plugin.

Questions:
Why does the 'WPML Multilingual CMS' plugin delete the order meta data?
How can I prevent 'WPML Multilingual CMS' from deleting the order meta data?