Trial of Sekhemas last boss phase skip

About 4 out of 6/7 of my last boss fights have been deaths due to the boss suddenly activating his one shot kill ability out of nowhere.

Saw some posts about this and people assume it happens when you deal too much damage and skip the hourglass phase or when it basically becomes two phases instead of one. Usually happens when he speaks his voice line "The sands of time waits for no one" twice.

Just very frustrating and sucking out my desire to play the game as in the game's current endgame state the Trial of the Sekhemas is the only one I currently enjoy putting time in.

Just posted about this myself today actually.

For me, it seemed to occur if I burst boss down below 25%, he starts the timestop phase normally. Upon completion, he almost immediately starts it again, but this time when touching the middle of the map to start the phase when you are normally frozen to view the hourglasses he reappears and just one taps you. It's almost like the game is reading the 2nd time stop as you failing the first one.

Anecdotal experience, of course.

also just replied on another person's post. He mentioned it was during the second hourglass phase. I also recall I did "too much" damage when this happened