Contact Sync loop under Android 5.0.2 with Nine

Hello,
i have several users including myself, where the following setup works flawless for every sync. But of course, i have one user, where the setup does not work.:p:confused:
Nine was used since lollipop had no native client anymore for activesync and gmail wasn't at all working.

Zimbra Version 8.6.0
Zextras Version 1.10.2

Android Nexus 4/5/10 (5.0.2) with Nine as the client SW.
Syncing of mail, contacts and even tasks works great, even multiple calendars in the own account gets synced.

But for this one user, the contacts don't show up. Everything else works.

No error in mailbox.log is showing up.

Account Log is created, just waiting for someone to look at them.

Kind regards

Marwel