Nextcloud (Docker version) no video thumbnails

Nextcloud version: 20.0.7
Operating system and version: Ubuntu 20.04.2 LTS on Raspberry Pi 4

The issue you are facing:

None of my videos uploaded onto my Nextcloud (installed via Docker) are showing any thumbnails. Images are fine and thumbnails are generated, but not for videos.

Tried looking for a solution, but every solution out there assumes you don’t use Docker so it doesn’t apply for my case.

Is this the first time you’ve seen this error? (Y/N): Yes

Steps to replicate it:

  1. Upload video.
  2. No thumbnails are generated.

The output of your config.php file in /path/to/nextcloud:

<?php
$CONFIG = array (
  'htaccess.RewriteBase' => '/',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  array (
    0 =>
    array (
      'path' => '/var/www/html/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 =>
    array (
      'path' => '/var/www/html/custom_apps',
      'url' => '/custom_apps',
      'writable' => true,
    ),
  ),
  'memcache.distributed' => '\\OC\\Memcache\\Redis',
  'memcache.locking' => '\\OC\\Memcache\\Redis',
  'redis' =>
  array (
    'host' => 'redis',
    'password' => '',
    'port' => 6379,
  ),
  'instanceid' => 'private',
  'passwordsalt' => 'private',
  'secret' => 'private',
  'trusted_domains' =>
  array (
    0 => 'mydomain.com',
  ),
  'datadirectory' => '/var/www/html/data',
  'dbtype' => 'mysql',
  'version' => '20.0.7.1',
  'overwrite.cli.url' => 'http://mydomain.com',
  'dbname' => 'private',
  'dbhost' => 'private',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'private',
  'dbpassword' => 'private',
  'installed' => true,
  'twofactor_enforced' => 'true',
  'twofactor_enforced_groups' =>
  array (
  ),
  'twofactor_enforced_excluded_groups' =>
  array (
  ),
  'enable_previews' => true,
  'preview_max_x' => 4096,
  'preview_max_y' => 4096,
  'preview_max_filesize_image' => 50,
  'enabledPreviewProviders' => [
        'OC\Preview\Movie',
        'OC\Preview\PNG',
        'OC\Preview\JPEG',
        'OC\Preview\GIF',
        'OC\Preview\HEIC',
        'OC\Preview\BMP',
        'OC\Preview\XBitmap',
        'OC\Preview\MP3',
        'OC\Preview\TXT',
        'OC\Preview\MarkDown',
        'OC\Preview\OpenDocument',
        'OC\Preview\Krita',
  ],
);

Want to know, when can I add the function of video thumbnail?

Bump? No one here knows the solution?