while syncing a address book , maintained by SOGo (5.0) no contact ware shown due to an incompatibility of RFC 6578 compliance.

SoGo's response is not compliant with RFC 6578, which specifies the sync-collection report.

Quote:

The content of each DAV:response element differs depending on how the member was altered:
For members that have changed (i.e., are new or have had their mapped resource modified), the DAV:response MUST contain at least one DAV:propstat element and MUST NOT contain any DAV:status element.

Now looking at the response i got, it reports the cards like this:

<D:response>
        <D:href>
                /SOGo/dav/yyyyyy@zzzzz.de/Contacts/personal/sabre-vobject-79024419-6f71-4dba-a7ef-06104101d416.vcf
        </D:href>                                 
        <D:status>
                HTTP/1.1 201 Created
        </D:status>                                             
        <D:propstat>
            <D:prop>
                <D:getetag>
                        "gcs00000002"
                </D:getetag>
            </D:prop>                                       
            <D:status>
                    HTTP/1.1 200 OK
            </D:status>
        </D:propstat>
    </D:response>