The bug with a hero power

I’ve played the adventure “Tomb of Terror” (heroic) for Reno with the hero power “Arcane Craftiness”. The enemy laid the card “Imp gang boss”, I used my hero power - the first missile hit the Imp gang boss, he spawned the imp, and the second missile hit precisely this (spawned) imp, killing him, but the power didn’t repeat. Fix this bug (if a minion dies from this hero power, then it must be repeated). Thanks!