I think your problem is with your strong params:
def item_params
params.require(:item).permit(:id, :content, :kind, questions_attributes: [:content, :helper_text, :kind, answers_attributes: [:content, :correct]])
end
Basically, when you pass a deep nested form (where you have multiple dependent models), you'll have to pass the attributes as part of the other model's attributes. You had the params as separate