Elasticsearch - No value specified for terms query - ruby-on-rails

Question

Calling all elasticsearch experts:
Environment:
elasticsearch (6.8.3)
rails 5.1.7
Linux
We changed our association from our user model to the person model from a has_one to a has_many. We did not however remove the person_id column as this can cause other issues (e.g. running code from another branch that still tries to use it)
It seems no matter what we do to the index definitions for ElasticSearch, if any null values exist in person_id (which they do now with all newly added records) we get
"No value specified for terms query"
I have confirmed this by populating that column with an integer value resulting in no error occurring.
I have removed person_id from any indexes I even removed any reference to the peoples table in the ES index declaration but it appears that as soon as ES sees there is an association to a Person model and it sees the person_id column, it tries to use it.
Besides writing an arbitrary value in the person_id column, does anyone else have a better approach? We DO NEED to search fields in the associated Person model (peoples table) but since it's a has_many, it shouldn't be using the person_id column which is no longer relevant.
We also considered reversing the search from Person to User but that would require a LOT of recoding.
Is it possible a newer version of ES will fix it? We'd probably have to upgrade the ES server as well if we update the gem right?
Here is the association:
has_many :people, :class_name => Person.to_s # I believe it's this class name that's causting it to try to use the person_id column
Here is the index definition
def as_indexed_json(_options = {})
as_json(
:only => %i[id email portal_id],
:include => {
:portal => { :only => %i[name slug] },
:people => { :methods => %i[first last full_name], :only => %i[first last full_name] },
:events => { :only => [:id] },
:account_brokerage_firms => { :only => [:id] },
:brokerage_firms => { :only => [:id] },
:roles => { :methods => [:role_name], :only => [:role_name] }
}
)
end
settings AUTOCOMPLETE_SETTINGS do
mapping :dynamic => 'false' do
indexes :id, :type => 'long'
indexes :email, :type => 'text', :analyzer => 'email'
indexes :portal_id, :type => 'long'
indexes :people do
indexes :first, :type => 'text', :analyzer => 'autocomplete'
indexes :last, :type => 'text', :analyzer => 'autocomplete'
indexes :full_name, :type => 'text', :analyzer => 'autocomplete'
end
indexes :portal do
indexes :name, :type => 'text', :analyzer => 'autocomplete'
indexes :slug, :type => 'text', :analyzer => 'autocomplete'
end
indexes :events do
indexes :id, :type => 'long'
end
indexes :account_brokerage_firms do
indexes :id, :type => 'long'
end
indexes :brokerage_firms do
indexes :id, :type => 'long'
end
indexes :roles do
indexes :role_name, :type => 'text', :analyzer => 'autocomplete'
end
end
end
# end of elastic search settings
# this function assumes there is only one user role between a user and an account