The Bukkit event CreatureSpawnEvent is no longer firing for Villager spawns other than via a Spawn Egg.

Recreating the error:

1) Fresh Spigot install, with no other plugins.

2) Create a basic plugin with the following event registered to the PluginManager:

@EventHandler(priority = EventPriority.MONITOR)
public void onCreatureSpawnEvent(CreatureSpawnEvent event) {  
    if(event.getEntityType() == EntityType.VILLAGER) { 
        Bukkit.broadcastMessage(event.getSpawnReason().name()); 
    } 
} 

3) Confirm that spawning a villager with a spawn egg broadcasts the message "SPAWNER_EGG"
4) Locate the nearest village. (Use /locate Village)
5) Travel to the village and note that no message broadcasts occur at all (There should be CHUNK_GEN or NATURAL appearing).