Librarian villager "enchanted book trade" gives bookshelf instead.

The librarian villager will have a menu option, at first level, for an enchanted book, but when I click on the trade, the emeralds go into the slot, and a bookshelf appears in the other slot, not an enchanted book. Happened multiple times with the same villager, even after rerolling trades. When the trade is taken, the price of the enchanted book is taken, but only a bookshelf is received.