I mentioned this earlier, but here’s gif proof of it in-game. On the Lich King, Colossus, and Witch it works fine, just with these two bosses. Both of these bosses the only way you can aggro them is either run into them (which you can’t do on the second tree boss in the gif) or baton throw. Just posting this because Riley asked and I’m unsure if it’s intended or not 
Do the crescendos hit the bosses if they are already in combat? Or it just goes through them when they’re not in combat?
In combat they go through aswell.
Okay,and just to be sure it happens every time, not just on occasion? Just getting info so I can track down the bug.
Yep, tried crescendos multiple times during both bosses in combat. Just goes through.