如何修复'include'不显示文件内容?

I am trying to include a google map in my php file. I have it set up and when I run it, the map works perfectly with no errors, but when I include it in my php file, nothing comes up, no errors, just blank.

I have tried using require, include and include_once, and even just putting all the contents of my map file into my php file rather than including it, none of these work. I am getting no errors so I am unsure of why this is happening.

 <?php include_once '../google_map.php';?>

I expect my google map to display along with other contents in my php file. I didnt post the code for my map as it works fine on its own, just not in an include, please let me know if I should post it.

New: This is the google_map.php

<!DOCTYPE html>
<html>
  <head>
    <title>Simple Map</title>
    <meta name="viewport" content="initial-scale=1.0">
    <meta charset="utf-8">
    <style>
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 50%;
         width: 40%;
      }
      /* Optional: Makes the sample page fill the window. */
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
   <script> 
   var map; 
 function initMap() 
{ 
map = new google.maps.Map(document.getElementById('map'), 
{
 center: {lat: -34.397, lng: 150.644}, zoom: 8 }); } initMap(); </script>
    <script src="https://maps.googleapis.com/maps/api/js?key=MYKEY&callback=initMap"
    async defer></script>
  </body>

</html>

and this is how I am including it:

  <?php 
               if ((include '../google_map.php') == TRUE) {
    echo 'OK';

}
         ?>

When google_map.php is run itself, it works and shows the map. When i use include in a different php file, it does not work, and I only get 'OK' in which OK comes from the code above

including a file sometimes is 'tricky' - from the PHP manual, https://www.php.net/manual/en/function.include.php Example #6, try this....

$string = get_include_contents('../google_map.php');

// Now, you can just 'echo' it and see the results
echo $string;

function get_include_contents($filename) {
    if (is_file($filename)) {
        ob_start();
        include $filename;
        return ob_get_clean();
    }
    return false;
}

I'm working on a very similar 'include' and this is the one that worked for me. It brings in variables too.