The Bulk Import module for batch registration of items and media in Omeka S has a bug in versions 3.3.28.0 through 3.3.33.2 that prevents media from being registered. If you need to register media, you will need a workaround such as using version 3.3.27.0 or earlier.

After creating an issue about this problem, the bug was promptly fixed:

https://gitlab.com/Daniel-KM/Omeka-S-module-BulkImport/-/issues/10

As of July 1, only the source code on GitLab has been updated, but it should be added to the GitHub Releases soon. Please be aware of this when using this module.

If you want to install from the GitLab source code, please refer to this README. Specifically, navigate to the modules directory and run commands like the following:

$ cd modules/
$ git clone https://gitlab.com/Daniel-KM/Omeka-S-module-BulkImport.git BulkImport
Cloning into 'BulkImport'...
remote: Enumerating objects: 7580, done.
remote: Counting objects: 100% (1627/1627), done.
remote: Compressing objects: 100% (746/746), done.
remote: Total 7580 (delta 1056), reused 1163 (delta 750), pack-reused 5953
Receiving objects: 100% (7580/7580), 8.08 MiB | 20.02 MiB/s, done.
Resolving deltas: 100% (5095/5095), done.
$ cd BulkImport/
$ composer install --no-dev
Installing dependencies from lock file
Verifying lock file contents can be installed on current platform.
Package operations: 12 installs, 0 updates, 0 removals
  - Downloading composer/installers (v2.1.1)
  - Downloading oomphinc/composer-installers-extender (2.0.1)
  - Downloading box/spout (v3.3.0)
  - Downloading codemirror/codemirror (5.65.1)
  - Downloading flowjs/flow-php-server (v1.0.3)
  - Downloading flowjs/flow.js (2.14.1)
  - Downloading hakre/xmlreaderiterator (v0.1.11)
  - Downloading mikehaertl/php-tmpfile (1.2.1)
  - Downloading mikehaertl/php-shellcommand (1.6.4)
  - Downloading mikehaertl/php-pdftk (0.9.2)
  - Downloading mtdowling/jmespath.php (2.6.1)
  - Downloading phpoffice/phpword (0.18.3)
  - Installing composer/installers (v2.1.1): Extracting archive
  - Installing oomphinc/composer-installers-extender (2.0.1): Extracting archive
  - Installing box/spout (v3.3.0): Extracting archive
  - Installing codemirror/codemirror (5.65.1): Extracting archive
  - Installing flowjs/flow-php-server (v1.0.3): Extracting archive
  - Installing flowjs/flow.js (2.14.1)
  - Installing hakre/xmlreaderiterator (v0.1.11): Extracting archive
  - Installing mikehaertl/php-tmpfile (1.2.1): Extracting archive
  - Installing mikehaertl/php-shellcommand (1.6.4): Extracting archive
  - Installing mikehaertl/php-pdftk (0.9.2): Extracting archive
  - Installing mtdowling/jmespath.php (2.6.1): Extracting archive
  - Installing phpoffice/phpword (0.18.3): Extracting archive
Package box/spout is abandoned, you should avoid using it. No replacement was suggested.
Generating autoload files
1 package you are using is looking for funding.
Use the `composer fund` command to find out more!

I hope this serves as a useful reference when using BulkImport.