1) With a book open, search for a word and select one of the hits to jump to the page. (Or if a search is already active, simply jump to another page by selecting another search hit from the Search Results menu.)
2) Open the nav drawer.
3) Press the back button. Instead of the nav drawer closing as expected, it stays open but the position in the book jumps back to the page it was on prior to jumping to the search hit. The nav drawer doesn’t close until the back button is hit again.
From the forums: