Facebook send to messenger renders in html but button not shown

My Facebook "send to messenger" button is not showing in browser, i have almost tried all the solutions given in stackoverflow.

My app is in development mode, page is added, webhook added and verified.

Below is my html code :

<!DOCTYPE html>
<meta content="width=device-width, initial-scale=1" name="viewport" />
<title>My Website</title>
  window.fbAsyncInit = function() {
      appId            : '1234567890',
      autoLogAppEvents : true,
      xfbml            : true,
      version          : 'v9.0'
<script async defer crossorigin="anonymous" src="https://connect.facebook.net/en_US/sdk.js"></script>
      fbmessegner button starts here 
      <div class="fb-send-to-messenger" messenger_app_id="1234567890" page_id="0987654321" data-ref="testingmessenger<?php echo time(); ?>" color="blue" size="large"> </div>
      ends here

When i inspect elements i can see the script has loaded but its not showing, see below screenshot:

enter image description here

My browser screenshot :

enter image description here

Kindly advise


Source: Facebook SDK Questions