I've been getting a bug with CoS since around the update of LH 1.2 (so I'm assuming CoS 1.2a). While playing the Beastlord class (and perhaps any class with Earth spells), the Nature's Call ability doesn't work anymore. It used to work just fine with CoS before 1.2, but now when you cast it in battle, the casting animation and sound effect still occurs, but no creatures are ever summoned.
As I remove CoS from the Mods folder, the ability works just as intended. It only doesn't work while this mod is active. Not sure if other abilities are affected as well, as I've only noticed this with Nature's Call.