I've been having weird issues with a build i made, in strange ways too, sometimes i kill a group of enemies yet i don't receive the buff at all(i wonder if this is maybe cause i'm getting the kills with scorch rather than the melee hit?), sometimes my melee kickstart doesn't trigger at all(no clue why it rarely happens though). The duration is just too short, because of that you rarely get the full use of the exotic, even with a build focused on getting your full melee energy back immediately. It's just kind of sad to see when compared to the titans and hunters, titans have the hammer they can just pick up, no build effort to get melee's back and hunters exotic liars handshake triggers differently, sure it's less damage but it's still very strong and spammable easily. Not to mention the build aspects hunters and titan can add to improve on the exotics.