Jamanra dissappear after my character death

Was fighting jamanra for the first time, die to it twice, the third time entering jamanra, he was gone.

The previous fight, i died to his "windy with ads phase". Entering the arena, seeing the stairs entrance available. Going in just show a long stretch of empty sandy area with nothing inside, then suddenly new quest popup?

Happened exactly the same here. It looked like we skipped the boss fight in this way.

same thing just happened to me on cruel, died to him and then when i respawned he was gone and the quest had progressed

edit: scripted, you fight him again later