Trying to get some custom AR callbacks to trigger corresponding handlers in an observer

dashboard_observer.rb

class DashboardObserver < ActiveRecord::Observer
  observe :user
 
  def after_activate(user)
    DashboardService.update_metrics
  end 
end

user.rb

class User < ActiveRecord::Base
  include User::Authentication
 
  define_model_callbacks :upgrade, :downgrade, :cancel, :activate, :deactivate
  
  #large swaths of code
  
  def activate!
    run_callbacks :activate do
      self.update_attribute(:active, true)
    end
  end
end

Note, I'm trying to create a custom callback in User. When a user is activated, I want the 'activate' callback to fire and to be handled in my DashboardObserver. As the code stands, the observer never sees the callback get raised.

Note, I'm using the define_model_callbacks method above. I get the same results if I use define_model.

And, yes, I've correctly registered the observer in application.rb