Double tap transmuting

After transmuting 5 cards i get no next level card. And at the end of each wave i get no cards anymore.

At the end of the wave, does it say "Auto Transmute: Tinker"? To change auto-tansmute settings, open the menu during a game and long-press on the button for a type of card. I.e. long-press on potions to change potion auto-transmute settings.

Thanks Fuzzy! Yes this sounds a lot like auto transmute.