Cant "leap" over bosses ground slam attack - Bug ID 3317677292

Video:
https://www.youtube.com/watch?v=2xmcqT1fGs8

BUG ID #3317677292

Fighting +4 difficulty T15 savannah boss.

Set up several storm lances and knowing his slam attack was coming. I timed my thunderous leap to go over the slam and detonate my lances.

It was gonna be sweet!

And then.... Somehow his ground-based shockwave on-shot me at the literal apex of the leap (like 3+ meters in the air).

This can't be intended right?

Here are some key frames:
https://imgur.com/a/CgBtvVi


1 Frame before "slain" - Clearly far above the ground attack



1 Frame later - I am now "slain" (from full health)



1 or two frames later - Sprite has been teleported to the ground back closer to where I leaped from? Game possibly did count my character as actually being in the air...