After editing a calender entry in GroupWise, the event duplicates - but only with Samsung S6edge (Android 5 and 6); it does not duplicate in GroupWise; but it also duplicates an all other devices, which this user syncs mit Groupwise.
Any ideas?

We tried already:
- re-initalising the user on GMS
- deleting the user from GMS (after first sync - events are OK)
- deleting the account on the phone
- GW folder check with dsapp
- GW check
- .... can't remember everything (factory reset is not an option at the moment!)


We are running release 14.2.1 Build 270 on SLES 12 SP2
and we have 12 POAs, 442 users and 619 devices syncing