PUT request stopped working

PUT requests stopped working. GET requests work fine.
Receiving:
Fatal error: Uncaught Automattic\WooCommerce\HttpClient\HttpClientException: Syntax error in...

Code:

require(APP . '/lib/vendor/autoload.php');
use Automattic\WooCommerce\Client;
/*
$woocommerce = new Client(
    'https://xxx.com', 
    'xxx', 
    'xxx',
    [
        'wp_api' => true,
        'version' => 'wc/v3',
    ]
);


$data = [
		'status' => 'Completed'
	];
			
print_r($woocommerce->get('orders/xxx');
print_r($woocommerce->put('orders/xxx', $data));

Start by reproducing the PUT call through lib/vendor/autoload.php and Automattic\WooCommerce\Client, comparing it with the working GET request and capturing the full HttpClientException response. No source file or test is named; done means identifying the PUT failure cause and adding a regression test that verifies the request succeeds or reports the corrected error.