Originally Posted by MHC
EDIT: Figured it out - it worked all along, it just didn't bring the anchor to the top of the page - ADE navigates so my subhead is in the middle of the page. Any way to have the subhead at the top? Or is this just an ADE glitch?
I think you're misunderstanding the difference between scrolling media and paged media.
Book readers act like paged media (e.g. printed pages); element positioning is computed only once when you first open the book, so that page 65 is always page 65. (*)
When clicking a link to an anchor, a reader behaves as though you turned to the page containing that anchor using the "next page" button. So if the subheading is halfway down the page, it appears halfway down the page just as it would if you turned to that page in a printed copy of the book.
If you want the subhead to be at the top of the page, you would need to insert a page break before the heading to force it to always be at the top of the page.
(*) As a special exception, changing the reader's font style/size settings, margin settings, etc. forces the reader to lay out the book's content again.