開発環境で変更できるemailが本番では変更できない

Question

Rails 5.0.2で開発し、Herokuに公開しています。

アカウント周りはdeviseを利用しています。
今ぶつかっている問題

Userが登録済みのemailを変更する仕様を入れています。localでの開発環境（development）では問題なく変更されるのですが、本番（production）ではemailのupdateがされないという問題にぶつかっています。原因があるとすると、deviseだとは思っているのですが、解決策わからず、お分かりの方御指南頂けますと幸甚です。

deviseではdatabase_authenticatable, registerable, recoverable,rememberable, trackable, validatable, omniauthable, omniauth_providers => [:facebook], confirmable（productionのみ）を利用しています。
Code(model, table, controller)

### User modelとtable
== Schema Information

Table name: users

  id                     :integer          not null, primary key
  email_for_index        :string           not null
  family_name            :string
  given_name             :string
  family_name_kana       :string
  given_name_kana        :string
  user_name              :string           not null
  address                :string
  user_icon              :text
  start_date             :date
  end_date               :date
  suspended              :boolean          default(FALSE)
  created_at             :datetime         not null
  updated_at             :datetime         not null
  email                  :string           default(""), not null
  encrypted_password     :string           default(""), not null
  reset_password_token   :string
  reset_password_sent_at :datetime
  remember_created_at    :datetime
  sign_in_count          :integer          default(0), not null
  current_sign_in_at     :datetime
  last_sign_in_at        :datetime
  current_sign_in_ip     :inet
  last_sign_in_ip        :inet
  provider               :string
  uid                    :string
  image                  :text
  confirmation_token     :string
  confirmed_at           :datetime
  confirmation_sent_at   :datetime
  unconfirmed_email      :string
  failed_attempts        :integer          default(0), not null
  unlock_token           :string
  locked_at              :datetime


class User < ApplicationRecord
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable,
         :omniauthable, :omniauth_providers => [:facebook]
  if Rails.env.production?
    devise :confirmable
  end

  mount_uploader :user_icon, UserIconUploader

 validates :user_name, presence: true, uniqueness: { case_sensitive: :true },
  length: { minimum: 1, maximun: 20, allow_blank: true }
  #, format: { with: /\A[A-Za-z]\w*\z/, allow_blank: false }

  before_validation do
    self.email_for_index = email.downcase if email
  end

  def self.new_with_session(params, session)
    super.tap do |user|
      if data = session["devise.facebook_data"] && session["devise.facebook_data"]["extra"]["raw_info"]
        user.email = data["email"] if user.email.blank?
      end
    end
  end

  def self.from_omniauth(auth)
    where(provider: auth.provider, uid: auth.uid).first_or_create do |user|
      user.email = auth.info.email
      user.password = Devise.friendly_token[0,20]
      user.given_name = auth.info.name
      user.user_name = auth.info.name   # assuming the user model has a name
      user.image = auth.info.image # assuming the user model has an image
      user.user_icon = user.image
      # If you are using confirmable and the provider(s) you use validate emails,
      # uncomment the line below to skip the confirmation emails.
      # user.skip_confirmation!
    end
  end

  def self.new_with_session(params, session)
    super.tap do |user|
      if data = session["devise.facebook_data"] && session["devise.facebook_data"]["extra"]["raw_info"]
        user.email = data["email"] if user.email.blank?
      end
    end
  end

  def active?
    !suspended? && start_date <= Date.today && (end_date.nil? || end_date > Date.today)
  end
end

class User::AccountsController < User::Base
  before_action :authenticate_user!
  before_action :search_preparation

  def show
    @user = current_user

    respond_to do |format|
      format.html {
        render :show
      }
      format.json {
        render json: {status: true}
      }
    end
  end

  def edit
    @user = current_user
  end

  def update
    @user = current_user
    @user.assign_attributes(user_params)
    if @user.save
      redirect_to :user_account, notice: "基本情報を更新しました。"
    else
      render "edit"
    end
  end

  def icon_edit
    @user = current_user
  end

  private def user_params
    attrs = [
      :email_for_index, :email, :family_name, :given_name, :family_name_kana, :given_name_kana,
      :user_name, :address, :user_icon, :remove_user_icon
    ]
    params.require(:user).permit(attrs)
  end
end

Answer 1

config/initializers/devise.rbのconfig.reconfirmable = trueをconfig.reconfirmable = falseにしたら解決しました。