amp-img images not showing on iphone

Question

I'm having an issue with images not loading on iPhone browsers. Works absolutely fine while testing through chrome and other browsers on Android phones. I keep getting the console error "Failed to load: image - v0.js:127"

Below is the html code of an image, you will see there's nothing out of the ordinary but yet the images won't load specifically on iOS devices.

<div class="left-column">
    <a href="test/en/amp/car/aston-martin-db9">
        <amp-img 
            src="test/assets/img/upload/car_images/1569501218.webp" 
            alt="Aston Martin DB9" 
            width="508" 
            height="340" 
            layout="responsive">
            <amp-img fallback 
                src="test/assets/img/upload/car_images/1569501218.png" 
                alt="Aston Martin DB9" 
                width="508" 
                height="340" 
                layout="responsive">
            </amp-img>
        </amp-img>
        <h4 class="center-text small-text red">Aston Martin DB9</h4>
    </a>
</div>

Any help would be greatly appreciated... I can give working URLs if required but I don't understand/can't find any information on what would be causing this v0.js:127 error solely on iOS devices.