json_decode return null on valid string?

Question

Hi I have this simple string called $response1:

{"SN":"5054494EA805743F","MAC":"CC:19:A8:xx:xx:xx","customerName":"John doe ","id":"6666","serviceID":"1000","jobid":"12345"}

Essentially I get this string from a curl request but when I do "$ree = json_decode($response1); print_r($ree); return null.

Here is the snippet

                $response1 = curl_exec($ch2);
                $ree = json_decode($response1);
                print_r($dee);  
                print_r($response1);

JSON checkers says the string is okay, and json_last_error() returns 0

What is going on here ?

All the code as requested

 <?php

            $ch2 = curl_init();
            //initiate http curl connection.
            curl_setopt_array($ch2, array(
                CURLOPT_URL =>  "http://x.x.x.x/Testingsomething.php",
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_ENCODING => "",
                CURLOPT_MAXREDIRS => 10,
                CURLOPT_TIMEOUT => 30,
                CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
                CURLOPT_CUSTOMREQUEST => "POST",
                CURLOPT_POSTFIELDS => "------WebKitFormBoundary7MA4YWxkTrZu0gW\r\nContent-Disposition: form-data; name=\"JobId\"\r\n\r\nXXXXXXX\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW--",
                CURLOPT_HTTPHEADER => array(
                "cache-control: no-cache",
                "content-type: multipart/form-data; boundary=----WebKitFormBoundaryXXXXXXXX",
            ),
            ));
                //$response1 = curl_exec($ch2);
                //$ree = json_decode($response1, true, JSON_THROW_ON_ERROR);
                //print_r($ree);    
                //echo $ree["ontserial"];

                try {  
                  $response1 = curl_exec($ch2);
                  $ree = json_decode($response1, true, 512, JSON_THROW_ON_ERROR);  
                    print_r($response1);
                    print_r($ree);
                    echo $ree;
                }  
                catch (\JsonException $exception) {  
                  echo $exception->getMessage(); // displays "Syntax error"  
                }