Zarokh, the Temporal double hourglass insta-kill

I was fighting the final boss of The Trial of Sekhemas, got him down to half hp in about the first 5 seconds of the fight. He does his hourglass move where he says "the sands of time" and you stand in the center, then I proceed to pick up the 6 blue hourglasses on the ground before the time expires. He comes back like normal and I begin attacking him again. He gets down to about 1/4 hp within the next 2 seconds and then begins another hourglass move. I haven't ever seem him do 2 hourglass moves back to back in the roughly 50 runs I've done so far. So before he even finishes unfreezing time and laying down all the hourglasses, he re-appears and insta-kills me with the "boop on the nose" move as if I failed the hourglass encounter. It looked like because he started another one instantly after I finished the first one, that the game used the original timer for the original hourglass encounter and thought the time ran out. I don't know for sure that is why, but it definitely seems like a bug.