polymorphic association saving issue using mongoid

gistfile1.rb

#Models
class Event
  include Mongoid::Document
  has_and_belongs_to_many :organizations, index: true
  belongs_to :location, polymorphic: true, index: true
end

class Organization
  include Mongoid::Document
  has_and_belongs_to_many :events, index: true
end

class Venue
  include Mongoid::Document
  has_many :events, as: :location, autosave: true
end

#Code

org = Organization.first
ven = Venue.first
evt = org.events.create(location: ven)
org.events.count #=> 1
evt.location #=> #<Venue...

# How can I make this include the event?
ven.events.count #=> 0

I could just do

ven.events << evt

But then I'd have to do that every time I created an event scoped from the organization.

Are you including the :class_name option in your Event model for the location?

Edit: Disregard, I just noticed that's a polymorphic relationship.