They just spin around a couple times and go in a random direction.

I'm using CB 1.2.5-R4.0 and these plugins:

Orebfuscator v1.4.5, AutorunCommands v3.0.3, PlugMan v1.7.0, RandomReward v0.1, CCLogger v3.0.0, ResExtras v1.0, Vault v1.2.16-b184, Multiverse-Core v2.4-b527, SimpleHelpTickets v0.9, ChunkVisualizer v0.1, ColourFireWorks v1.3.6, dynmap v0.37-1120, CensorShip v1.8, LazyRoad v0.8.1, Spectate v1.8, EndReset v1.0-rc2, EasyEnchant v1.2.1, DisguiseCraft v2.2, LegendaryLibrary v1.01, mcMMO v1.3.08-b857, Catacombs v2.5, VIP v1.0.4, Citizens v1.2, Jobs v2.8.4, LagMeter v1.8, ZeeSlag v1.2.0, CaptureThePoints v1.3.8, AlphaChest v1.12.0, WorldEdit v1164-15977e8, Courier v1.1.6, MobDungeon v1.1.4, GiveAll v2.0b1, Multiverse-Inventories v2.4-b165, Multiverse-NetherPortals v2.4-b530, PorteCoulissante v1.2.9, UtilityHats v0.9.1, SimpleCommandSigns v0.8, PermissionsEx v1.19.2, WorldGuard v624-18b5a4e, ChestRestock v2.3-SNAPSHOT-b49, TreasureHunt v0.9, ScrollingMenuSign v1.3.0, iConomy v7.0, HiddenCommandSigns v1.3, BookWorm v1.14, BKCommonLib v1.2, EnchantMore v1.0, SimpleSpleef v3.0.17, LegendaryItems v1.3_5 Beta, Herochat v5.5.0, AutoAnnouncer v1.7-03.23, HyperConomy v0.927, Essentials vDev2.9.296, MobRider v0.45.2-b43, CreeperHeal v5.0.1, MondoChest v0.5.3, Multiverse-Portals v2.4-b548, CraftBay v1.1.2, NoLagg v1.84, Residence v2.6.2, rescreative v0.1, Dynmap-Essentials v0.14, EssentialsSpawn vDev2.9.296, VanishNoPacket v3.10, LWC v4.2.1 (b700-git-MANUAL) (May 20, 2012), DeathChest v1.07, Dynmap-HeroChat v0.10, resfly v1.3, resperm v0.4, ResidenceSigns v2.3, MagicSpells v2.7-test, ResProtect v0.3, dynmap-residence v0.17

The plugin is due for an update ever since the new mob AI was added. It's on the todo list.

Plugin has been updated. Download the latest and give it whirl.