Technically don’t know if this is a bug or not, it’s entirely possible Bungie wants it this way. I was trying to put together a gunpowder gamble build and noticed that firefly kills on other weapons would add stacks to gambles charge, but when I threw on Ace to see how it fit into the build, it wasn’t adding stacks. I know the icon for its version of firefly is different from what ships on legendary weapons, and Aces version came out before subclass verbs were a thing, but wasn’t sure if this was an intended thing to keep it in line or if it was a bug from it being an older version of the perk.