While playing as Victor I bought the MK-2 and the Ultimate Hex-Core uprgrade for Victors personal item at once while i was dead. The game then only allowed me to upgrade one of my spells. This resulted in to of them not being able to upgrade for the rest of the game.
I buy 2 or all 3 hex-core upgrades at the same time constantly without issue. I would imagine you just pissed Viktor off by spelling his name wrong.
They might have forgotten the case where someone might buy multiple upgrades at once... which would be a pretty large oversight on their part.
i've never had this problem buying two upgrades at once, probably a bug
