Animated gif not animating

Site: https://revolutionaryengines.com/

The animated gif is an engine cross section down at the bottom of the page. It should be going through cycle.

This is the image by itself.

https://revolutionaryengines.com/wp-content/uploads/2016/05/CheesemanPlug-anim.gif

The image is NOT resized. Here is the code for it:

<div style="margin: 0 20px 0 50px;">
     <a href="/technology/">
          <img src="https://revolutionaryengines.com/wp-content/uploads/2016/05/CheesemanPlug-anim.gif" />
     </a>
</div>

What am I doing wrong?