An Even Larger Man doesn't work

Hey Blizzard :), the Hearthstone Achievement “An Even Larger Man” does not work for me. I produced a 42/42 ‘old’ C’thun in casual wild, and when nothing happened, i sacrificed some ranked points and finally produced a 28/28 in ranked wild. A 20/20 should have been enough, but the achievement is still unfinished.
Cheers!

Did you still have the minion at the end of the turn?

Also, 19.0 Patch Notes

  • Achievements – Achievements are broken up into categories and subcategories. As you’d expect, the Game Modes and Adventures categories can only be completed within their specified modes. The more general Progression and Gameplay categories can be completed in Ranked, Arena, and Duels modes.

Thanks for the reply! Yes i did, in both cases, though the casual one won the game if i remember right.

This achievement is really weird. I had a poisonous minion with divine shield and I think the game counted it as infinite hp and mana so it counted for the achivement.