Generated php results appear and then promptly disappear - php

Question

So I am trying to create a tutorial bookmarker project. The idea is that the bookmarked tutorials are supposed to load when the page opens. I am trying to display the results from the mysql database using php, for some reason the results only display for half a second and then disappear.
I have spent ages trying to figure out how to fix it and have had no luck. I think it might have something to do with the while loop but not sure.
I have created a class that contains the simple load bookmarks function.
<?php
class Bookmarked {
private $con;
public function __construct($con) {
$this->con = $con;
}
public function loadBookmarks(){
$str = "";
$data = mysqli_query($this->con, "SELECT * FROM bookmarked ORDER BY id DESC");
$count = mysqli_num_rows($data);
if($count == 0){
echo "No bookmarks saved";
}
while($row = mysqli_fetch_array($data)){
echo "In while loop";
$tutname = $row['tutname'];
$tutdescription = $row['tutdescription'];
$tuturl = $row['tuturl'];
$date_added = $row['date_added'];
$str .= "<div class='well'>
<h3>$tutname</h3> <hr> <br>
<p>$tutdescription</p> <br>
<a class='btn btn-primary' href='#'><i class='fas fa-check'></i></a>
<a class='btn btn-default' href='$tuturl' target='_blank'><i class='fas fa-search'></i></a>
<a class='btn btn-danger' href='#' onclick='deleteBookmark()'><i class='fas fa-trash'></i></a>
</div>";
}
echo "Out of while loop";
echo $str;
}
}
?>
I am trying to call it as shown below
<?php
include("includes/header.php");
include("includes/classes/Bookmarked.php");
?>
<div class="header">
<h3 class="text-muted">Tutorials Bookmarked</h3>
</div>
<div class="row">
<div class="col-lg-12">
<div id="bookmarksResults">
<?php
$bookmark = new Bookmarked($con);
$bookmark->loadBookmarks(); //Calling the loadBookmarks() function
?>
</div>
</div>
</div>
</body>
</html>
I tried search for an answer but couldn't find anything. If this isn't clear enough I will explain further.