Contact synchronization phone to owncloud does not work



The synchronization from the phone to the owncloud does not work. It is only synchronizing in the other direction but the synchronization should be in both ways.

The contact list in owncloud is still empty after several weeks of using owncloud now. The calendar and tasks synchronisation is working without problems in both ways. For test purpose I created a contact in owncloud and it was synchronised to my phone. Even in this contact that has the connection symbol of DAVdroid in it, changes in the phone are not sent back to owncloud. What could be the source for this synchronization problem?

Android version: 7.0
Device model: Samsung Galaxy S7
ownCloud app version: 2.4.0
DAVdroid Version: 1.6.2-gplay
Server configuration was done through owncube


I think this issue should be handled through the OwnCube support.