Yea, You're probably talking about situation on Poker, right? But you was a lil bit outside the bubble (your head). But it's true that not always bubble protect Helga's attack. On the same map and same game before I've created a bubble and I died inside (I was for sure fully covered by bubble - 3rd person doesn't lie :V).
Maybe by those open holes in bubble Helga can attack us inside, but I'm not sure that.
Also about Helga and Bubbles - Helga's attack is really fast, sometimes it's hard to create a bubble in time. Maybe should be increased a lil bit time of Helga's attack or speed up a lil bit creating a Bubble.
We had this problem many times and I don't know why.
Maybe Some part of your body is outside or you are to slow or a grenade was inside..
100 Percent you was Little bit ouside of your Bubble. and i think this is not a bug. =>Helga is in your bubble and throw balls and you die. that is normal too.