Why is my catch-all route not working for some routes?

I have this in routes.rb:

resources :emergencies, except: [:new, :edit, :destroy], defaults: { format: :json }
match '*path', to: 'application#page_not_found', via: :all

I also have this in application.rb:

config.exceptions_app = self.routes

And my application_controller.rb looks like this:

class ApplicationController < ActionController::Base
  def page_not_found
    render json: { message: 'page not found' }, status: :not_found
  end
end

I have a set of test suites that tests the :new, :edit, and :destroy route. The routes for :edit and :destroy pass, returning the message page not found as expected, but the :new route returns null. Infact, anything like /emergencies/anything would render null, but something like /emergences/new/new would work correctly. Any idea on why this is happening and how I can fix it so that the route /emergencies/new is hitting the page_not_found action?