I bulk smushed all images and now some images aren't appearing. And it's worse in Firefox. For example, in this post 2 the first 2 images are grey boxes. In Chrome it's just the first image missing. In this post with several images, some images have just a grey box. More images are missing in Firefox than in Chrome. I've just checked posts randomly and discovered this. I just checked that page again and fewer images are missing but there are still some missing. Why is this happening?