Helena 44P (1P) active frame glitch...?

So this is me taking a brief break from the Uncharted 4 awesomeness and messing around in training.

To my knowledge of this game, a strike can't be held after it's connected and the damage has been calculated. I'm aware of the absurd amount of active frames on Helena's 1P(P) iteration, and now I'm just confused as to whether this is an exception or a glitch and if it's already been discovered? Was practicing guaranteed stuff on slip zone, and the regular 1PP seems to work just fine.