Do you have any hermit crabs or shrimp in your tank? If so they are a huge problem with feather dusters. I just got rid of my crabs and shrimp due to them constantly bothering my feather dusters. I would see the crab actually drag the dusters across the tank.
My two ocellaris clowns never bother my dusters, I have two large dusters.
Have you seen them actually nip the ends of the dusters?
If it is the clowns for sure, sorry I cannot help you with that. Hopefully someone here will be able to help you.
:happyfish