I have a 20x15x20 room with no openings and cure a Zombie Villager in that room with only a lectern to choose from. There are no villages or personal places within 200 blocks so no other profession blocks but that lectern to choose. The villager picks fisherman, then butcher, Fletcher, and lastly the 4th villager chose armorer.

This doesn't seem like the way things are supposed to work as a month ago I was able to put them in a room at my base with a profession block, and even though other profession blocks were around my base they chose the one in the room.