Essence trapped monsters

Since the last patch when i encounter essence trapped monsters they are empowered by the essences but when I beat them they drop 1 less essence. for example if they are empowered by only 1 essence then they drop 0 essences. if they are empowered by 2 essences they drop only 1 essence. this is true for trapped monsters found naturally and also for those found when i select essence in the map device. Is this intended?