unkillable enemy in act 3 canals

In act 3 when i am going through the canals as the druid bear one of the monkey enemies is unkillable no matter how many attacks and doesnt even show up when i put my mouse over it. It does damage to me and i cannot do damage to it. please fix. its not a big deal since its a squishy but still if this was a larger enemy it would be frustrating.