Blood Mage Cast Stagger

I find it that while using life as the sole resource for casts, at times when I have to cast more repeatedly (my main spell has 0.6 cast time, with total casts per second on 1.56) the casts are interrupted mid animation which then seem to travel onto the next attempt to cast.

Can it be that because the character is loosing life to cast at an accelerated rate that this damage is being interpreted as external or too much and staggering ourselves out of cast? Asking bc if even feels like so when testing in an environment without any mobs.

This happens a lot when using hexblast.

Anyone one else?