Ok, following you're advice I finally managed to get the SQL to return the expected records.
SELECT DISTINCT tblBuyers.ID, tblBuyers.Email, Nz([tblBuyers].[FirstName],"") & " " & Nz([tblBuyers].[Surname],"") AS Name, Max(tblApartments.DateUpdated) AS MaxOfDateUpdated
FROM tblApartments...