Nextcloud desktop client shows sync is done but it isn't

Nextcloud version (eg, 20.0.5): 27.1.6
Operating system and version (eg, Ubuntu 20.04): webhost
Apache or nginx version (eg, Apache 2.4.25): webhost
PHP version (eg, 7.4): 7.4

The issue you are facing:
Yesterday I opened a file in the synced folder implemented by nextcloud desktop client. The file shows the green synced symbol. But on every other computer it’s the old version. In nextcloud itself it’s the old version. The file isn’t locked.

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

Steps to replicate it:

  1. Opened and edited a file
  2. Saved it
  3. Sync shows to be done but it isn’t

The output of your Nextcloud log in Admin > Logging:

No error is shown

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

$CONFIG = array (
  'instanceid' => '1',
  'passwordsalt' => 'Password1',
  'secret' => 'SuperSecretSecret',
  'trusted_domains' => 
  array (
    0 => 'ushur.thegreatest.ever',
  'datadirectory' => '/directory/data',
  'dbtype' => 'mysql',
  'version' => '',
  'overwrite.cli.url' => 'ushur.thegreatest.ever',
  'dbname' => 'mydb',
  'dbhost' => 'localhost:1',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'ushur',
  'dbpassword' => 'SuperSecretPassword1',
  'installed' => true,
  'profile.enabled' => true,
  'default_language' => 'de',
  'default_locale' => 'de_DE',
  'versions_retention_obligation' => '90, auto',
  'account_manager.default_property_scope' => 
  array (
    'email' => 'v2-private',
    'displayname' => 'v2-local',
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 2,
  'updater.secret' => 'UshurIsTheBest',

The output of your Apache/nginx/system log in /var/log/____:

Don't have it. It's webhostet

Output errors in nextcloud.log in /var/www/ or as admin user in top right menu, filtering for errors. Use a pastebin service if necessary.

There seems to be no error tracked by nextcloud. Just nothing happens.