A buddy and I are doing the daily heroic; juggler is on, and he is using Ice Breaker. No ammo dropped the entire run for me, and ironically, only special ammo was dropping for him while using Ice Breaker. I was sad.
I forgot to mention, I used sunsinger and killed at least 5 lower rank vex with 1 grenade throw, and didn't have any orbs drop at all.
I feel like juggler is on anytime that I am playing. I rarely get ammo drops; even when I'm killing 2-3 times more than my fireteam members.