Transaction ID not being returned by deliver method

[deanlaw]

Laravel 12, php 8.4.19, guzzlehttp 7.12.1. Deliver method works, and the fax is deliverd, but the transaction id is null, so there is no way to track the status.

$client = new Interfax\Client(['username' => '...', 'password' => '...']);
$fax = $client->deliver([
    'faxNumber' => '+442086090368',
    'file' => __DIR__ . '/../tests/Interfax/test.pdf'
]);

$transactionId = $fax->id; 

The $transactionId value is null. It appears that the returned Location Header is not being properly parsed.