Is there a difference of opinion on applying the letters of hams in tajweed?

I have noticed from my pakistani teachers not teaching the letters of Al-Hams and some even advising not doing an exasperation when there is a sukoon on the letter (example tabbath pakistani reciter ) , whereas my Arab teachers teach that it is required in tajweed ([\[example tabbath arab reciter mishary\]][3] ). Does there exist a difference of opinion on this issue? Riwayat: Hafs 'an Asim