[horde] ActiveSync e-Mail problem

[lst_hoe02 at kwsoft.de]

Hello,

testing the ActiveSync part we found the following problem with Cyrus  
2.4.17 and iOS 6.1.3 (iPhone):

The Account creation and events work fine, but e-Mail will only sync  
at startup with a somewhat random subset of the mails in the user  
mailbox. Further new mail will not show up on the Phone. The  
ActiveSync debug log show something like this:

2013-07-08T18:28:04+02:00 INFO: All synckeys confirmed. Continuing with SYNC
2013-07-08T18:28:04+02:00 DEBUG: [4031] O  <Synchronize>
2013-07-08T18:28:04+02:00 DEBUG: [4031] O   <Status>
2013-07-08T18:28:04+02:00 DEBUG: [4031] O    1
2013-07-08T18:28:04+02:00 DEBUG: [4031] O   </Status>
2013-07-08T18:28:04+02:00 INFO: [4031] Initializing state for  
collection: INBOX, synckey: {51dac604-8df0-4fe1-bfaf-08dad5a44353}38
2013-07-08T18:28:04+02:00 INFO: [4031] Loading state for synckey  
{51dac604-8df0-4fe1-bfaf-08dad5a44353}38
2013-07-08T18:28:04+02:00 INFO: [4031] Initializing message diff  
engine for f1443163 (INBOX)
2013-07-08T18:28:04+02:00 INFO: [4031]  
Horde_Core_ActiveSync_Driver::getServerChanges(INBOX, 1373300374,  
1373300884, 1370881684, 0)
2013-07-08T18:28:04+02:00 INFO: IMAP status: Array
(
     [uidnext] => 31702
     [uidvalidity] => 989246025
     [highestmodseq] => 1493
)

2013-07-08T18:28:04+02:00 INFO: [4031] Found 0 message changes in f1443163.

and with a new mail arrived:

2013-07-08T18:31:07+02:00 INFO: All synckeys confirmed. Continuing with SYNC
2013-07-08T18:31:07+02:00 DEBUG: [4031] O  <Synchronize>
2013-07-08T18:31:07+02:00 DEBUG: [4031] O   <Status>
2013-07-08T18:31:07+02:00 DEBUG: [4031] O    1
2013-07-08T18:31:07+02:00 DEBUG: [4031] O   </Status>
2013-07-08T18:31:07+02:00 INFO: [4031] Initializing state for  
collection: INBOX, synckey: {51dac604-8df0-4fe1-bfaf-08dad5a44353}38
2013-07-08T18:31:07+02:00 INFO: [4031] Loading state for synckey  
{51dac604-8df0-4fe1-bfaf-08dad5a44353}38
2013-07-08T18:31:07+02:00 INFO: [4031] Initializing message diff  
engine for f1443163 (INBOX)
2013-07-08T18:31:07+02:00 INFO: [4031]  
Horde_Core_ActiveSync_Driver::getServerChanges(INBOX, 1373300374,  
1373301067, 1370881867, 0)
2013-07-08T18:31:07+02:00 INFO: IMAP status: Array
(
     [uidnext] => 31703
     [uidvalidity] => 989246025
     [highestmodseq] => 1494
)

2013-07-08T18:31:07+02:00 INFO: [4031] Found 0 message changes in f1443163.

So highestmodseq and uidnext reflect the change, but horde still does  
not found a new message???

System is latest stable Horde/IMP with Cyrus IMAP Server and  
ActiveSync client iOS 6.1.3 (iPhone 4S).

Thanks for any help

Andreas