AWS S3を使用しHerokuにデプロイしたが、画像の投稿ができない

現在Ruby on Railsで画像を投稿するサイトを作成しており、Herokuでデプロイしました。画像のアップロードにはcarrierwaveを使用し、保存先としてAWS S3を設定しています。開発環境では画像の投稿、削除、プロフィール画像の変更等は問題なくできるのですが、本番環境だとこれら全てができなくなっています。

該当コード

imag_uploader.rb

class ImageUploader < CarrierWave::Uploader::Base
  # Include RMagick or MiniMagick support:
  # include CarrierWave::RMagick
  include CarrierWave::MiniMagick

  if Rails.env.development?
    strage :file
  elsif Rails.env.test?
    storage :file
  else
    storage :fog
  end

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url(*args)
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process scale: [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end

  # Create different versions of your uploaded files:
  # version :thumb do
  #   process resize_to_fit: [50, 50]
  # end

  version :medium do
    process resize_to_fill: [325, 225]
  end

  version :thumb do
    process resize_to_fit: [150, 150]
  end

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  def extension_whitelist
    %w(jpg jpeg gif png)
  end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end
end

carrierwave.rb

require 'carrierwave/storage/abstract'
require 'carrierwave/storage/file'
require 'carrierwave/storage/fog'

if Rails.env.production?
  CarrierWave.configure do |config|
    config.storage :fog
    config.fog_provider = 'fog/aws'
    config.fog_directory = 'nekojita'
    config.fog_credentials = {
      provider: 'AWS',
      aws_access_key_id: ENV['AWS_ACCESS_KEY_ID'],
      aws_secret_access_key: ENV['AWS_SECRET_ACCESS_KEY'],
      region: ENV['AWS_DEFAULT_REGION'],
      path_style: true
    }
  end
end

git push heroku master

中略
remote:        [1/4] Resolving packages...
remote:        [2/4] Fetching packages...
remote:        info fsevents@1.2.9: The platform "linux" is incompatible with this mo
dule.
remote:        info "fsevents@1.2.9" is an optional dependency and failed compatibili
ty check. Excluding it from installation.
remote:        [3/4] Linking dependencies...
remote:        warning " > webpack-dev-server@3.8.1" has unmet peer dependency "webpa
ck@^4.0.0".
remote:        warning "webpack-dev-server > webpack-dev-middleware@3.7.1" has unmet
peer dependency "webpack@^4.0.0".
remote:        [4/4] Building fresh packages...
remote:        Done in 20.95s.
remote:        Compiling…
remote:        Compiled all packs in /tmp/build_aac9acab0414ea445452535543160c24/publ
ic/packs
remote:        Asset precompilation completed (31.94s)
remote:        Cleaning assets
remote:        Running: rake assets:clean

remote: -----> Detecting rails configuration
remote:
remote: ###### WARNING:
remote:
remote:        You set your `config.assets.compile = true` in production.
remote:        This can negatively impact the performance of your application.
remote:
remote:        For more information can be found in this article:
remote:          https://devcenter.heroku.com/articles/rails-asset-pipeline#compile-s
et-to-true-in-production
remote:
remote:
remote: ###### WARNING:
remote:
remote:        You set your `config.active_storage.service` to :local in production.
remote:        If you are uploading files to this app, they will not persist after th
e app
remote:        is restarted, on one-off dynos, or if the app has multiple dynos.
remote:        Heroku applications have an ephemeral file system. To
remote:        persist uploaded files, please use a service such as S3 and update you
r Rails
remote:        configuration.
remote:
remote:        For more information can be found in this article:
remote:          https://devcenter.heroku.com/articles/active-storage-on-heroku
remote:
remote:
remote: ###### WARNING:
remote:
remote:        We detected that some binary dependencies required to
remote:        use all the preview features of Active Storage are not
remote:        present on this system.
remote:

remote:        For more information please see:
remote:          https://devcenter.heroku.com/articles/active-storage-on-heroku
remote:
remote:
remote: ###### WARNING:
remote:
remote:        No Procfile detected, using the default web server.
remote:        We recommend explicitly declaring how to boot your server process via
a Procfile.
remote:        https://devcenter.heroku.com/articles/ruby-default-web-server
remote:
remote:
remote: -----> Discovering process types
remote:        Procfile declares types     -> (none)
remote:        Default types for buildpack -> console, rake, web
remote:
remote: -----> Compressing...
remote:        Done: 97.3M
remote: -----> Launching...
remote:        Released v18
remote:        https://nekonosita.herokuapp.com/ deployed to Heroku
remote:
remote: Verifying deploy... done.
To https://git.heroku.com/nekonosita.git
   25f867c..f611c1d  master -> master