So i made a villager area in my house and put tons of lecterns everywhere and trapped villagers,while most became librarians some became farmers, i was near a lake but im not sure if that effects it i had no composters or any farm anywhere so im not sure what happened. When they became farmers the lecterns had green sparkles above them. Not a visual. They trade farmer things too.

Steps to reproduce: build a 1 by 2 hole the villager can fit in 

2:build a lectern in front 

3:spawn villagers

Expected results:you will have librarians

Observed results: some villagers arent the correct job but some are