From my experience, it is not the skill that causing it. Doesn't matter which skill i use, if i attack the boss before it attacks (except if it is hit by thunder break, well it is not like i am attacking the boss with thunder break), the glitch happened.
And sorry if i cause misunderstanding. The skills i mentioned on my post (Blizzard and Cloud Kill) are not the skill that causing glitch, but the skill that can still be used to damage the glitched mobs.
Normally with this glitch it is only the skill that caused it that can damage the mob so I'm not sure I would remove those two from the list just yet.
I think this bug might have something to do with the new groggy system as like I said above sometimes the boss won't switch between rage/groggy/normal status right away and can't be damaged during that time