Webp conversion not working

Siteground automatically delivers WebP images in “transparent” mode. This means the URL doesn’t change, and it’s highly likely that their setup automatically delivers the original JPG/PNG when using the “save image as…” option.

To confirm that EWWW IO has converted an image to WebP, simply add .webp to the end of the URL (right-click, choose Copy Image Address to get the URL).
So for example, if your image is at https://example.com/wp-content/uploads/2021/04/my-image.jpg
put https://example.com/wp-content/uploads/2021/04/my-image.jpg.webp in your address bar and see if it loads.

To confirm that Siteground is delivering the images in the WebP format, you can use the Chrome Dev tools. We have a little demonstration of that here: https://youtu.be/ywBkIhCSAJ4