When you are looking at your wishlist there is a drop down box which will be showing the number of books on your wishlist. If you open that up you will see "show related editions", click on that and related editions should show. I hope that helps.
You probably changed it accidentally. Once you've selected it again it should stay like that. If you look at another member's wishlist and change the settings so that related editions don't show then when you go back to your own wishlist it won't show related editions, so it's possible you did that. On the other hand it could have been a small blip with the site.
