E-books and poetry just don’t get along as well as e-books and prose. It’s those line breaks, poetry’s defining feature. The problem is a simple sounding one, but really tough to solve. Because the same e-book has to work on many different screens and devices on which readers can change the font and size of the text, it’s impossible to guarantee the line will display as the poet intended.
Of course, poetry publishers have the same problem with print books—sometimes poets’ lines are wider than a book’s trim size (take Walt Whitman or Allen Ginsberg), but there’s a convention to solve this: when a poetic line continues over the edge of a printed page, it’s indented on the next line. It’s been surprisingly hard to reliably recreate this indenting in an e-book, to make sure poems keep the integrity of their lines when they appear on screen.