Flameblast PVP hits even outside the blast

Im playing with Flame Blast in open PVP and I have gotten reports from opponents that they get hit even if they are outside the blast. I assume that this is a graphical bug.

I also experience this myself when I play against others who play with Flame Blast. I have stun immunity.

The people who've reported it have been on the same US server (which I also am on) so the lag should be at a minimum.