Hi,
Please forget about what I said about the latest version of LSCWP plugin. I was mistaken about your issue.
I’ve looked at your web page and see a webp version image, which indicates webp replacement did indeed happen. There are two possible reasons why the other photos are not replaced by the webp version.
1) Not all of the images in your media library have a corresponding WebP version, because you didn’t turn on Create WebP Versions at the beginning. Therefore the photos that were optimized before WebP Versions Creation was enabled remain in the media library without any WebP version. If these images are called for your web page, then webp replacement naturally won’t take place at all, simply because the WebP version doesn’t exist.
2) Regardless whether you enabled Create WebP Versions at the beginning, certain images still don’t have WebP versions; this is normally because the webp versions are found to be bigger than their corresponding JPG versions and thus get discarded.
Nevertheless, if you verify that the images in question all have a corresponding WebP version in the media library but still not loaded, it’ll be a problem indeed and we’ll go from there to troubleshoot it.
Regards.