I synchronize my Thunderbird Address Books (Windows PC) via the Radicale server with an Android phone with DAVx5. From Thunderbird to Android, sync works correct. New items and changes show up on Android. But from Android to Thunderbird, nothing syncs. From Android to the Radicale server, all seems well, because the changes show up in the Radicale collection, as show when you download the .vcs file. So the problem seems between Radicale and Thunderbird. Can someone please help to debug this problem? E.g. is there a log of Thunderbird for the sync of the addressbook? Thanks!