Pig zombies are not spawning using MM they are just spawning vanilla. Similar to when the 1.11 version came out Skeletons and Zombies would just spawn vanilla and would not go through MM.
MM Version: Latest development build (2.6)
ML Version: 0.0.1-SNAPSHOT
Spigot Version: 1.11
Client Version: 1.11
Error Log: http://hastebin.com/ucufazaraz.bash
Mob Config: http://hastebin.com/obonahinux.pl
Skill Config: http://hastebin.com/raqokocive.scala
MM Version: Latest development build (2.6)
ML Version: 0.0.1-SNAPSHOT
Spigot Version: 1.11
Client Version: 1.11
Error Log: http://hastebin.com/ucufazaraz.bash
Mob Config: http://hastebin.com/obonahinux.pl
Skill Config: http://hastebin.com/raqokocive.scala