Cannot Disenchant Hearthstone Cards

Some cards cannot be disenchanted, for example, Diamond cards, cards obtained from promotions, or exclusive rewards from the Tavern Pass or Hearthstone adventures. A card is typically non-disenchantable when it is uncraftable. You can confirm if your card is uncraftable by checking the Hearthstone Wiki.

Mass Disenchant Button Missing?

The mass disenchant button will not appear if you don't have anything to mass disenchant. You can only mass disenchant if you have at least 3 copies of the same card. Otherwise, you need to disenchant the cards one-by-one.