Why update_post_meta is not working?

Hi all.
Do their action in order to Woo. It is necessary to update the value of the custom field.
code like this
......
 add_filter('woocommerce_order_actions', [__CLASS__, 'addCreateDealOrderAction']);
 add_action('woocommerce_order_action_create_deal', [__CLASS__, 'handleCreateDealOrderAction']);
......

public static function addCreateDealOrderAction($actions)
{
 $actions['create_deal'] = 'Create deal in Teamleader';
 return $actions;
}

 public static function handleCreateDealOrderAction($order)
{
 update_post_meta($order->get_id(), 'my_field', 'bla bla');
 }

Cause of action, the field does not change its value. Also tried using ACF update_field().
But. if I do this
var_dump( update_post_meta($order->get_id(), 'my_field', 'bla bla') );
 die;

I see true on screen and the field is updated.
April 3rd 20 at 17:17
1 answer
April 3rd 20 at 17:19
Solution
Well, Yes. The fact that together with the implementation of the action, why it works and update the item, i.e. sends the entire form. And then the fact that you first work out action, and then update the product. So the field. which I need to update first to be removed from $_POST, because later it will ground again.

public static function handleCreateDealOrderAction($order)
{
if(isset($_POST['my_field"]))
unset($_POST['my_field']);

 update_post_meta($order->get_id(), 'my_field', 'bla bla');
 }

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