accepts_nested_attributes + polymorphic association

im having an issue where my my polymorphic associations arent being
deleted when using accepts nested attributes
there are other accepts_nested_attributes being used and they are
deleting fine, just the polymorphic association
before i go down the path of intense thrashing at this a known
issue or problem?

i was so wrapped up in the polymorphic + nested attributes, i forgot
:dependent => :destroy on the model i was having issues with