Amanamu storm bug

There is a loot bug with the Amanamu rare monsters.
If you kill them while they are in the storm they only drop liege..
If you kill them outside the storm they drop other omens like omen of light, abyssal echo, dextral necromancy etc.
Being the only one that drops the lucrative loot it's super annoying to try and get him out of the storm and pry you kill him before he recreate the storm.
Its making abyss very annoying.