Bug Report - "Oversoul - Apex is needed to open the door"

Just reporting something that seems as a bug to me, hope you guys can take a look at it.

Killing Oversoul on Cruel with a party member, i thought i could die so i opened a portal. Started to hit him, when he got very low on life i died and respawned at the town, took the portal back and the other party member had killed him while i was teleporting. The door was open, but when i clicked on it, said i must have the Apex to get through the door and thats it, nothing happens.

Thank you for your time, and good day to you all

I had exactly the same issue, now stuck in the darkness of act 2 ruthless.

I had this happen in cruel, turns out I had forgotten to grab the apex from Alira (since I helped her). Once I grabbed it and went back, I got through no problem. Is the Apex in your inventory?