What I expected to happen was...:
unlocked librarians normaly change there trades or if you remove the work station and place it back they change there trades for all kind of different books. 

What actually happened was...:
out of around 40+ librarians i have they are all only giving me Smite book, Bane of arthropods and punch books im not able to get any other books apart from these 3. 

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...