I am using Nextcloud 16.01 as CALDAV and CARDDAV source with the Calendar, Contacts and Tasks inside of Netxtcloud. There are really working fine. On my Linux workstation I am using Lightning add-on togther with the “Provider for CalDAV & CardDAV” add-on. And of course DAVX5 for synchronisation of calandars and addresses. I was satisfied with this setup unril I lost a lot of contacts during multi-way synchronisation:
My wife was adding severals contacts to her mobile phone into the defined DAVX5 address book. I tried to get them but instead of receiving the new adresses and phone numbers a lot of other contcacts have been deleted.
Do you know how to debug this issue??