Pag upper fret ang buzz, hindi naccorrect ng truss rod adjustment yan. Lower fret area & middle part lang ang pwede macorrect ng truss rod.
Your guitar might need shimming on the neck pocket, or baka raised tongue yan (warping at upper fret area of neck) in that case, a luthier can fix it best. Gagawin dyan, aalisin yung frets, babawasan yung fingerboard mo sa upper frets na nagccause ng buzz, then ibabalik yung same frets na inalis.