Laravel 5.1: Guzzle 6 return response is not working

I'm using Gazzle 6 with Laravel 5.1 and I'm having a strange behaviour returning my data from the APIs I'm using. This is my code:

$data = array(
    'id' => '112233'
);

$from = \Carbon\Carbon::now()->subDays(1)->format('d/m/Y');
$to = \Carbon\Carbon::now()->subMonths(1)->format('d/m/Y');

$first_report = $this->client->post('http://ift.tt/1HJjTo9', [
    'auth' => ['myemail@email.com', 'mypassword'],
    'form_params' => ['data' => json_encode($data)]
]);



$second_report = $this->client->get('http://ift.tt/1N6nc5M', [
    'query' => [
        'account_auth_token' => '000011122223333444455556667778889999',
        'start_date' => $to,
        'end_date' => $from
    ]
]);

return array(
    'first_report' => $first_report,
    'second_report' => $second_report
);

If I return the data as an array like the previous one the first_report and second_report are empty. But if I return only for example

return $first_report;

or

return $second_report;

The data is returned correctly for each report but I don't know what is the issue there, because I have tried with: json_encode or even return $response()->json... but still not working.

Do you have any idea about what's going on?

via Chebli Mohamed