I confirm this made ingo 3.2.12 work against a cyrus sieve for user@domain.
Unless LOGIN breaks other common cyrus servers, perhaps this should be 
the default or at least documented in backends.php together with the 
part which does explain hooks.php nicely.

None at Ingo (authentication is done via Net_Sieve), but at your Sieve 
server, so you need to start looking there.

After changing 'logintype' => 'PLAIN', to  'logintype' => 'LOGIN, it 
works again!

So, the new questin is now. ;) What's the difference between PLAIN and 
LOGIN at ingo

Since last update to ingo 3.1.1 my users can't access and modify their 
sieve-rules.

While a user tries to change an existing script, he receives the 
following error-message: "Authentication failed."
My IMAP-server reports:

Jun 16 21:42:27 vml000170 dovecot: auth: 
passdb(n3rd@it-ignorant.org,10.0.0.90,master): Attempted master login 
with no master passdbs (trying to log in as user: n3rd)
Jun 16 21:42:29 vml000170 dovecot: managesieve-login: Disconnected 
(auth failed, 1 attempts): user=<n3rd@it-ignorant.org>, method=PLAIN, 
rip=10.0.0.90, lip=10.0.0.170, TLS

I didn't change my setup, whitch worked fine the last month.

On a second brand new installation I've the exactly the same problems.

My is setting is a multidomain-setup, so my clients uses their 
email-address for logins.

My backends.local.php:
/* IMAP Example */
$backends['imap'] = array(
     // ENABLED by default
     // Django : 2013-06-14
     // default: 'disabled' => false,
     'disabled' => true,
     'transport' => array(
         Ingo::RULE_ALL => array(
             'driver' => 'null',
             'params' => array(),
         ),
     ),
     'script' => array(
         Ingo::RULE_ALL => array(
             'driver' => 'imap',
             'params' => array(),
         ),
     ),
     'shares' => false
);

$backends['sieve'] = array(
     // Disabled by default
     // Django : 2013-06-14
     // default: 'disabled' => true,
     'disabled' => false,
     'transport' => array(
         Ingo::RULE_ALL => array(
             'driver' => 'timsieved',
             'params' => array(
                 // Hostname of the timsieved server
                 'hostspec' => 'vml000170',
                 // Login type of the server
                 'logintype' => 'PLAIN',
                 // Enable/disable TLS encryption
                 'usetls' => true,
                 // Port number of the timsieved server
                 'port' => 4190,
                 // Name of the sieve script
                 'scriptname' => 'ingo',
                 // Enable debugging. The sieve protocol communication 
is logged
                 // with the DEBUG level.
                // Django : 2013-06-14
                // default: 'debug' => false,
                 'debug' => true,
             ),
         ),
     ),
     'script' => array(
         Ingo::RULE_ALL => array(
             'driver' => 'sieve',
             'params' => array(
                 // If using Dovecot or any other Sieve implementation that
                 // requires folder names to be UTF-8 encoded, set this
                 // parameter to true.
                // Django : 2013-06-14
                 // default: 'utf8' => false,
                 'utf8' => true,
              ),
         ),
     ),
     'shares' => false
);

for using email-adress as login-name my hooks.php is:

     public function transport_auth($driver)
     {
         switch ($driver) {
         case 'timsieved':
//            // Example #1: Use full Horde username for password.
//            return array(
//                'username' => $GLOBALS['registry']->getAuth(null);
//            );
//
//            // Example #2: Use IMP password/username.
             $ob = $GLOBALS['registry']->call('mail/imapOb');
             return array(
                 'password' => $ob->getParam('password'),
                 'username' => $ob->getParam('username')
             );
         }
//
//        // DEFAULT: Use hordeauth (identical to not defining hook at all).
//        return true;
     }


     /**
      * Set the default addresses used for the vacation module.
      *
      * @param string $user  The username.
      *
      * @return array  A list of vacation addresses.
      */
//    public function vacation_addresses($user = null)
//    {
//        // Example #1: User has 2 vacation addresses.
//        return array($user . '@example.com', $user . '@foobar.com');
//    }

}

Why is horde/ingo trying to login as master? I've no master configured.