Pirate sirens' health does not decrease (The Witcher 3: Wild Hunt)

On the Skellige Islands in the "Band of Brothers" quest series, I can't kill the sirens. game 1.02, with me two skellig warriors, they also do not damage the sirens, they beat with a silver sword and steel and igni (pyromaniac and aard) do nothing to them. Tried to swing the trainer - did not help. I play on a high level of difficulty on these stupid sirenak used up all the potions that I stocked up on the giant. Help me find a bugfix