Jamanra, The Risen King BUG

Dear devs,

In a party of 2, we were fighting Jamanra, almost killed him. Got him down to 25% then we both died.

I resurrected and left the area, but my friend went AFK and stayed in dying state inside his room.

We come back 45 minutes later, to reinitiate the battle but to our surprise the boss is not there and marked complete. We did not collect any rewards, and just told us to go to the stairs leading to the gates which is covered by the desert storm.

The game progressed without us even completing the battle.
Furthermore, the impaler is also not present, presumed completed too.

I hope this can reset somehow.
We tried restarting the game, same issue persisted.

The NPC stays alive and kills Jamanra without you, as long as you keep the resurrect screen open.