Both Test 1 and 2 passed.
Thank you!

Changes have been made in Git (FRAMEWORK_5_2):

commit d78131805b1319db1227e8d6c69b524bbc45da21
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Mon Oct 20 22:20:05 2014 -0400

     Ensure we always have a start date for recurring tasks.

     Bug: 13636

  nag/lib/Task.php |    2 ++
  1 files changed, 2 insertions(+), 0 deletions(-)

http://github.com/horde/horde/commit/d78131805b1319db1227e8d6c69b524bbc45da21

There were some issues with missing fields in the recurrence 
structure. Fixed in Git.
I had no issues creating a recurring task on the client - it was 
propagated to the server correctly.

Using BB 3.1 emulator.

Changes have been made in Git (master):

commit 24f37c1476e75ff2605b16907ba1f1b5ae7df950
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Mon Oct 20 22:20:05 2014 -0400

     Ensure we always have a start date for recurring tasks.

     Bug: 13636

  nag/lib/Task.php |    2 ++
  1 files changed, 2 insertions(+), 0 deletions(-)

http://github.com/horde/horde/commit/24f37c1476e75ff2605b16907ba1f1b5ae7df950

Changes have been made in Git (master):

commit 7fc039a09b2e937e1450c7efe28f7ffcd0a11a12
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Mon Oct 20 22:18:07 2014 -0400

     Use TYPE_DATE_DASHES, and reorder fields.

     Bug: 13636

  .../Horde/ActiveSync/Message/TaskRecurrence.php    |    8 ++++----
  1 files changed, 4 insertions(+), 4 deletions(-)

http://github.com/horde/horde/commit/7fc039a09b2e937e1450c7efe28f7ffcd0a11a12

Changes have been made in Git (master):

commit a386978f0142d68722b952792ea079434ab38e9e
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Mon Oct 20 22:17:22 2014 -0400

     Add missing dayofmonth value for Task recurrence.

     Bug: 13636

  .../lib/Horde/ActiveSync/Message/Task.php          |    3 +++
  1 files changed, 3 insertions(+), 0 deletions(-)

http://github.com/horde/horde/commit/a386978f0142d68722b952792ea079434ab38e9e

Just tried the patch and it fixes the XML problem, but I did 2 tests 
and both failed.

Test1: Creating recurring task in Horde
Test 2: Creating recurring task in device

With the horde task, I see
NOTICE: [90657] Previous request processing for synckey 
{542e663e-c458-4948-96a6-1a73904cae96}19 failed to be accepted by the 
client, removing previous state and trying again.

but nothing happens. The device can't sync anything any more.

With the device task, nothing happens and there is nothing in the logs.

  I'm suspecting a problem with the device OS (10.3.1.821), unless 
someone else can confirm this.

Changes have been made in Git (master):

commit 773c5be013a7f91ad62a09bd3b7d2b339e0d6fac
Author: Michael J Rubinsky <mrubinsk@horde.org>
Date:   Mon Oct 20 18:29:51 2014 -0400

     Bug: 13636 These properties belong to 
Horde_ActiveSync_Message_TaskRecurrence.

  .../lib/Horde/ActiveSync/Message/Task.php          |   14 +------
  .../Horde/ActiveSync/Message/TaskRecurrence.php    |   46 
++++++++++++--------
  2 files changed, 29 insertions(+), 31 deletions(-)

http://github.com/horde/horde/commit/773c5be013a7f91ad62a09bd3b7d2b339e0d6fac

Finally found something in the logs
https://bugs.horde.org/ticket/13638

Connect Thunderbird and a BlackBerry device running 10.3.1 to a Horde account.

* Create task on BlackBerry.
* Confirm that you can see it both in Horde and TB
* Add recurrence to the task in TB: Fails
* Add recurrence to the task in Horde: Fails + breaks sync (task 
description is not updated per example)
* Add recurrence to the task on the phone: Same as Horde

Other scenario.
* Create recurring task on BlackBerry
* It never syncs

I only tried to add monthly recurrence
Activesync logs at default level show nothing.
PHP 5.4.34, FreeBSD