Event changed by Android gets not synced

I’ve installed zextras_suite-1.8.3 on the latest Zimbra (8.03) for testing purpose and im very close to buy. But there is one annoying bug.

I configured exchange on my android phone (Galaxy Nexus, Android 4.2.2) and everything works fine except the folowing:
When I edit an event on the phone, the changes are not synced. Deleteing or creating syncs perfectly. Also changes made on the web interface are synced to phone.