cURL response returns data in Postman, but returns NULL data set in PHP

Question

I'm trying to query a database from Google AppSheet via cURL. It works 100% in Postman (returns results), but when I copy the code into PHP it returns a NULL set (connects, but doesn't return results).

Postman screenshot w/data returned at bottom: https://imgur.com/9n5UUmB

PHP code as attempted, which returns NULL data...

<?php
 
$curl = curl_init();
 
curl_setopt_array($curl, array(
  CURLOPT_URL => 'https://api.appsheet.com/api/v2/apps/641c9c9f-XXXXXXXXXXXXX/tables/test/Action',
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'POST',
  CURLOPT_SSL_VERIFYPEER => 0,
  CURLOPT_POSTFIELDS =>'{
  "Properties": {
    "Locale": "en-US",
    "Timezone": "Eastern Standard Time"
  }
} ',
  CURLOPT_HTTPHEADER => array(
    'Content-Type: application/json',
    'ApplicationAccessKey: V2-XXXXXXXXXXXXX'
  ),
));
 
$response = curl_exec($curl);
 
 
 
//echo curl_getinfo($curl, CURLINFO_RESPONSE_CODE);
 
curl_close($curl);
echo $response;
 
 
echo "Error: ".curl_error($curl)."<br>";
echo "CURLINFO_RESPONSE_CODE: ".curl_getinfo($curl, CURLINFO_RESPONSE_CODE)."<br>";
echo "var_dump: "; echo var_dump($response)."<br>";
echo "var_dump/json_decode: "; echo var_dump(json_decode($response))."<br>";
echo "var_dump/curl: "; echo var_dump($curl)."<br>";
 
 
?>

Output of PHP code (from codeblock above): https://imgur.com/2joV4A8

The only thing I changed in the code after using Postman was to add "CURLOPT_SSL_VERIFYPEER = false", as the default value (true) was returning an error when I ran it on the webserver (SSL certificate problem: unable to get local issuer certificate). Using the "CURLOPT_SSL_VERIFYPEER = false" flag returns no error and a status of 200.

As you can see in the Postman screenshot, my test results are clearly visible in the table at the bottom (3 columns: RowNumber, A, B); this is what I'm expecting as an output. In addition, you'll see ("Output" screenshot) I'm not getting any errors, just a NULL return set.

I've tried running this in Postman, which works 100%. I expected this to return data in PHP (V.8.2.6 / IIS 10) however it returns the following (same as screenshot):

CURLINFO_RESPONSE_CODE: 200
var_dump: string(0) ""
var_dump/json_decode: NULL
var_dump/curl: object(CurlHandle)#1 (0) { }

I also tried the following and none of these fixed it:

• Set CURLOPT_SSL_VERIFYHOST to 'false'

• Added "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36", "Accept-Language:en-US,en;q=0.5"

• Removed "CURLOPT_ENCODING"

Any help is greatly appreciated. I spent literally the entire day trying to get this to work without luck.