It seems like its missing or there's an enormous discrepancy between the damage its doing (which I suppose is entirely possible).
In some cases, the damage is so insignificant that it looks like it is indeed missing.
The same fight with a different party, the damage is extremely apparent.
In the first case, most people are saying that its missing, and my response was "I didn't know it COULD miss."
To address your suggestion, I'm not dying in either case.
If it helps, the boss in question is Cad in Turn 1.
The reason I accepted to Miss possibility is because we had two scenarios:
1, there a wipe because of tank dying and the snakes fused: I LB'd for funsies since you lose the LB anyway.
At this point, even the damage on the fused snake was noticeable.
Same party run, which we cleared this time, I LB'd one of the snakes and LB did squat, IE making the argument that it missed appear valid.