Rust king Quest item despawn POE2

When I killed the rust king in ACT 1 cruel the adds killed me at the same time, and the Rust king dropped several items, including the quest item which disappeared and I can't even fight the Rust King again. So now I'm soft locked. Please help.

Same thing just happened to me on Act 1 (act 4). Died to rust kings attack just after he died and he's not spawning when i die. So cant get last rune. Any ideas on what to do?

Someone figured out how to unstuck form this situation?

I died after killing the rust king loosing the quest item. I left the area came back and teleported to the different checkpoints and the quest item was on the ground marked with a green checkpoint at a different location then i fought the rust king. Hope that makes sense and helps!