You may occasionally find Contact records in Outlook with this information:

"Synchronised from Workbooks"
"This record is incomplete because it did not match your filter"

Click to enlarge:

This is because they are the Primary Contact of a Task, Meeting or Case in Workbooks, but they don't match the filter you defined for People in the Workbooks Outlook Connector Synchronisation Control Panel (explained in the Installation Guide).

The records are incomplete and cannot be edited in Outlook.  If you'd like to edit the record amend your filter settings to include the record.