In her phonebook, my wife liked to use upper case letters for the persons entire first name than the conventional configuration for the last name and this created a problem that was driving me nuts until I figured it out. In other words, her entry for the person John Doe would be entered into her phonebook as JOHN Doe . When SYNC interprets the all upper case format, Sync expects the UPPER case letters to be individually enunciated. For my example for JOHN Smith, sync woud listin for "J" "O" "H" "N" This makes sense when you think about companies that only use letters to identify their business, like "AAA" or "ABC Taxi"
We edited her phonebook to eliminate the all upper case format and the problem was resolved.
Also, as others have said, Sync likes first and last names. Single names like "John" may yield undesired results but "John Doe" will make Sync happy.