get_post_meta() gets data from db table wp_postmeta instead of wp_wc_orders_meta

Hello,

I use the following code to add the contents of some custom checkout fields to my invoices and packing slips:

function custom_order_info_fields( $fields, $order ) {

	$custom_fields = array(
        array(
            'label' => 'Vergi Dairesi:',
	    'value' => get_post_meta( $order->get_id(), '_billing_vergidairesi', true ),
        ),
        array(
            'label' => 'T.C./Vergi No:',
			'value' => get_post_meta( $order->get_id(), '_billing_tckimlik_vergino', true ),
        ),
    );

    $fields = array_merge( $fields, $custom_fields );
    return $fields;
}

add_filter( 'wcdn_order_info_fields', 'custom_order_info_fields', 10, 2 );

The code works as intended except it gives empty values for the custom fields. There are no errors in debug logs, and when I dump some variables with:

var_dump(get_post_meta( $order->get_id(), '', false ));

I see the get_post_meta() returns data from my db table wp_postmeta instead of wp_wc_orders_meta where the custom fields are stored. wp_postmeta does have entries for every orderID that has a successful payment, because my payment gateway plugin stores them there, I’m not sure how or why.

Why does this happen and how do I make get_post_meta() return custom checkout fields?

Everything else seems to work fine. Below is my related config:

• WordPress 6.4.3
• WooCommerce 8.5.2
• Checkout Field Editor for WooCommerce 2.0.0
• Raft 1.1.1 (theme)
• Code Snippets 3.6.2
• Print Invoice & Delivery Notes for WooCommerce 4.8.1

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