iBooks Family Sharing Problem

I've shared some of my iBooks library with my wife

She wants to read a book and the prompt says, "This book is no longer shared with you. To read it you must buy it from the Book Store."

I've tried to purchase for her. Since I've already purchased, the store is not letting me re-purchase

In my family share settings, the iBooks icon is not listed in "shared with family"

Is someone able to explain to me how this happened and how to fix?

I just want to share books with her... Thanks!