I've noticed that sometimes in classic view a record will be marked "has no valid address". In RE NXT, the address will appear in the record, but there isn't anything telling the person that is viewing the record that the address is not actually valid. Also, if a person adds a new address in RE NXT and the record in classic view had been marked "has no valid address" the record will remain marked "has no valid address" unless the person that added the new address in RE NXT knows to go into classic view and uncheck that box.