Sending data via custom field not sending

Hi,

We’ve tested sending a basic string to each custom 1 and 2 fields using code according to the docs.

See our code below

add_filter( 'woocommerce_shipstation_export_custom_field_2', 'shipstation_custom_field_2' );
function shipstation_custom_field_2() {
	error_log( 'We are sending to SS' );
	return '_test_woo_to_ss';
}

And in our oder meta we have the a value for the meta key “_test_woo_to_ss”

We’ve tested this several times. Currently this is being called from a customisation plugin but the same code has been tested from theme functions.php too.

You can see we’re logging here. The call happens upon exporting to ShipStation.

I also went one step further and reported the next step of the process, see below.

add_filter( 'woocommerce_shipstation_export_custom_field_2_value', 'testing_shipstation', 10, 2 );
function testing_shipstation( $meta_value, $order_id ) {
	error_log( $meta_value . ' - For - ' . $order_id );
	return $meta_value;
}

This also gave the expected result. But the order is not updated in ShipStation.

Our orders are being exported as expected otherwise.

Any assistance on this would be greatly appreciated.