When you share eSlides on a website, the context for the eSlides (such as patient information, attached documents, specimens, and so on) are copied along with the eSlides. Although the context information usually transfers quickly, it make take a while for the images of the eSlides and specimens to transfer as these files are usually quite large.
On this page you can check on the progress of the file transfer from your local Aperio eSlide Manager location to the sharing site.