ZIMBRA FIXED THE ISSUES ON 11-11-2014: You can edit z-push core files so you don’t have to kill the Outlook process.

It is described on this SourceForge link http://sourceforge.net/p/zimbrabackend/discussion/998911/thread/9ae384f6/

edit lib/core/zpush.php like this:
vi lib/core/zpush.php
static private $supportedASVersions = array(
//self::ASV_1,
//self::ASV_2,
//self::ASV_21,
self::ASV_25,
self::ASV_12,
self::ASV_121,
self::ASV_14
);