Librarian Villagers' Trades Startover

Coastal Village Seed: -1813740965 (created v. 1.5.0 Beta) Survival Mode; Normal Difficulty; Infinite World Type.

I had 2 Librarian Villagers with which I had traded until all of their trades were revealed. The next time I tried trading with the Librarians the trades available started over at a cost of 30 plus emeralds for an enchanted book. None of the previous trades were available.