Fire Burst not hitting single bosses/conqs.

I’m not sure if it’s a visual bug or if it actually isn’t hitting bosses that don’t have adds and conquerors.
I’m playing a fire burst elementalist. Running maps is no problem, I throw storm brand down and I can visually see fireburst and herald of thunder falling from the sky hitting mobs. When I fight bosses and conquerors that have adds I see them both hitting and having visual effects. And they die at a good pace. But when I fight solo bosses with no added minions or targets the only thing I see doing damage is my storm brand. No herald of thunder and no fire burst. And they take forever to kill.
I’m on ps4.