Missing "Legacy of the Void" card back

After buying the StarCraft® II: Campaign Collection Digital Deluxe edition, I have not received the “Legacy of the Void” card back in Hearthstone, which should have been included. From searching the topic, it came to my attention that this is a known and ongoing issue for years now. Please fix it! I know it sounds silly, but using this cosmetic was a deciding factor in my purchase of the Digital Deluxe edition, and not being able to use it AND support not being able to help affected players just feels bad.

Thank you, and have a great day for everyone who comes across this!

I’m just guessing, but maybe you need to claim the cardback from the Gifts menu on the main battle.net screen?