Print_r doesn’t return anything; var_dump shows NULL

I’m new to web dev and I’m experimenting with Braintree webhooks. I’m using their create submerchant example code to create a submerchant and then supposedly a notification is supposed to reach my server that says if it was successful or not.

My method: I refresh the submerchant.php page (I’m using WordPress on a NameCheap server), which then echo‘s “Success!”. Then I go to the webhooks.php page and refresh it. However, the var_dump‘s only return NULL NULL and the print_r‘s don’t return anything. Why does print_r not show anything?

submerchant.php – this creates the submerchant when I set $one = 1 and set a new id for the submerchant

<?php

require_once(__DIR__ . '/../braintree/lib/Braintree.php');

Braintree_Configuration::environment('sandbox');
Braintree_Configuration::merchantId('A');
Braintree_Configuration::publicKey('B');
Braintree_Configuration::privateKey('C');

 function fd_create_sm() {

    $one;

    $one = 1;

    if($one=1) {

    $merchantAccountParams = [
      'individual' => [
        'firstName' => 'Janez',
        'lastName' => 'Doe',
        'email' => 'jane@14ladders.com',
        'phone' => '5553334444',
        'dateOfBirth' => '1981-11-19',
        'ssn' => '456-45-4567',
        'address' => [
          'streetAddress' => '111 Main St',
          'locality' => 'Chicago',
          'region' => 'IL',
          'postalCode' => '60622'
        ]
      ],
      'business' => [
        'legalName' => 'Jane's Ladders',
        'dbaName' => 'Jane's Ladders',
        'taxId' => '98-7654321',
        'address' => [
          'streetAddress' => '111 Main St',
          'locality' => 'Chicago',
          'region' => 'IL',
          'postalCode' => '60622'
        ]
      ],
      'funding' => [
        'descriptor' => 'Red Ladders',
        'destination' => Braintree_MerchantAccount::FUNDING_DESTINATION_BANK,
        'email' => 'funding@blueladders.com',
        'mobilePhone' => '5555555555',
        'accountNumber' => '1123581321',
        'routingNumber' => '071101307'
      ],
      'tosAccepted' => true,
      'masterMerchantAccountId' => "na",
      'id' => "green_ladders"
    ];
    $result = Braintree_MerchantAccount::create($merchantAccountParams);

    $result->success;
    if($result->success) {
    echo 'Success!';
    } else {

    print_r($result->errors);

            $errordata;
            echo '***********';
            $BT_Errors = new Braintree_Error_ErrorCollection($errordata);
            echo '***********';
            $BT_Errors->deepAll();
            echo '***********';
            $BT_Errors->onHtmlField("transaction[amount]");

    }

    $result->merchantAccount->status;

    $result->merchantAccount->id;
    // "blue_ladders_store"
    $result->merchantAccount->masterMerchantAccount->id;
    // "14ladders_marketplace"
    $result->merchantAccount->masterMerchantAccount->status;
    // "active"

    } else {
    return;

    }
 }

fd_create_sm();

?>

webhooks.php

<?php

var_dump($_POST['bt_signature']);
var_dump($_POST['bt_payload']);

print_r($_POST['bt_signature']);
print_r($_POST['bt_payload']);

?>