Combat Frenzy Charge Generation buged?

I play Invo with Combat Frenzy to generate Power Charges. Against normal monsters it works as intended.

Against Rares and Bosses however it just stops working and i cant say what the problem is.

I tried to only attack with ice strike, without mark and without bell. Even then, when i freeze the Boss it just doesnt give me a charge.

Even weirder, i linked the "empowered sparks" to check if that procs when i freeze and it sometimes procs without creating charges and i sometimes create charges without the spark proc.

Anybody else has experienced something similar? Maybe it is a Hollow Palm Bug? Havent tested it with a Staff.