Librarian Trading Bug

I created a Trading Hub and finally got a Librarian with Fortune 3 for Tier 1.

I made sure to trade with them first to the point of ranking up to Tier 2, then destroyed the lectern to place it a better spot. However upon destroying the Lectern the Librarian returned to being a villager. When I placed the Lectern back down the Villager turned into a Librarian without the Fortune 3 enchantment book available anymore. I had spent 20-30minutes attempting to get a librarian with Fortune 3 and successfully did so for  a bug to then reset them. As destroying the Lectern and placing again after that made the librarian remain as a librarian with the same items (not fortune 3)...