So everyone time I activate my mullet, my propellor hat activates and vice versa.

Any known fixes?

Mullet is not a hair, it's an a 3d item. You can not activate two 3d items attached to one bodypart at the same time (e.g. green hat + deal with it glasses, shutter shades and propeller hat won't work)

Ok, but this is still not helping the problem I am having.

try deactivating both maybe that will work then try to re-activate one of the items or maybe send it to another account eg. an alt account altho i dont recommend using this account ingame but you can try to create one and send it to that account then resend it to see if that helps