Eaten Alive would not let me sacrifice a creature, until I had low enough mana that the additional mana payment could not be satisfied.

During a PVP match in Starter Deck duels I attempted to use Eaten alive and pay the additional sacrifice a creature. I selected the target enemy creature to exile, and after that it aske you me to pay the additional cost. Instead of highlighting my creatures as options to sacrifice, the Auto pay option showed up, and it wanted me to tap a land. It would only let one be tapped and not go any further, as if the 1 creature cost was being misconstrued as a 1 mana cost. After playing another card to have my available mana lower than the other additional cost option of 3+1B, the sacrifice creature cost seemed to work as intended.

Platform: MTG Arena PvP
OS:PC/Steam
Game mode: PvP
Relevant card: Eaten Alive