Debug Requests not working, returns HTTP200 but empty response.

[PetervdPerk]

I'm following the debug example from the README.md
https://github.com/br33f/php-GA4-Measurement-Protocol#example

I do get a HTTP 200 response but the response is empty

int(200)
array(0) {
}

[br33f]

@PetervdPerk Please provide code reproducing this error.

[PetervdPerk]

<?php
use Br33f\Ga4\MeasurementProtocol\Service;
use Br33f\Ga4\MeasurementProtocol\Dto\Request\BaseRequest;
use Br33f\Ga4\MeasurementProtocol\Dto\Event\AddToCartEvent;
use Br33f\Ga4\MeasurementProtocol\Dto\Parameter\ItemParameter;

// Create service instance
$ga4Service = new Service('MEASUREMENT_PROTOCOL_API_SECRET');
$ga4Service->setMeasurementId('MEASUREMENT_ID');

// Create base request
$baseRequest = new BaseRequest();
$baseRequest->setClientId('CLIENT_ID');

// Create Invalid Event Data
$addToCartEventData = new AddToCartEvent();
$addToCartEventData
    ->setValue(99.99)
    ->setCurrency('SOME_INVALID_CURRENCY_CODE'); // invalid currency code

// addItem
$addToCartEventData->addItem(new ItemParameter([
    'item_id' => 'ITEM_ID',
    'item_name' => 'ITEM_NAME',
    'price' => 99.99,
    'quantity' => 1
]));

// Add event to base request (you can add up to 25 events to single request)
$baseRequest->addEvent($addToCartEventData);

// Instead of sending data to production Measurement Protocol endpoint
// $ga4Service->send($baseRequest); 
// Send data to validation endpoint, which responds with status cude and validation messages.
$debugResponse = $ga4Service->sendDebug($baseRequest);

// Now debug response contains status code, and validation messages if request is invalid
var_dump($debugResponse->getStatusCode()); 
var_dump($debugResponse->getValidationMessages());
? >

Of course I've replaced the MEASUREMENT_ID and api key.