Ok, so the title is a little wierd, but I don't really know what this feature is called. Basically, when you use the uploader on a page with multiple image (at least pixiv and twitter), it will generate upload pages for all the images on the page. For example, this page generated from a tweet with multiple images contains links to upload pages (like this one) for every image in the tweet. This is how it has always worked, and how I think it's supposed to work. Recently (I don't know when exactly), this feature no longer works with pixiv posts with multiple images. This pixiv post has two images, but the uploader only generates upload pages for each image individually (image 1 and image 2). I'm pretty sure this is a bug.