How do I stop iBooks skipping pages in continuous scroll mode?

When I download a book preview, then download the full book, continuous scrolling in the Books app skips tens or hundreds of pages around the preview end page. I've seen this in most (maybe all) books I've downloaded recently. This started some time before iOS 18.4.1, likely in the last few months. A workaround is to change to "curl" page turning mode. But I'm looking for a permanent fix, because flipping 100 pages is pretty annoying when I'm used to scrolling. Deleting and re-downloading the book doesn't work. I don't want to delete the app, because I'm not sure if all my books are stored in iCloud.