Quest Item Disappeared Can't Continue

Hi,

I was progressing through the Trial of Chaos quest and defeated the Chimera in Act 3. After it dropped the quest item, Chimera-Inscribed Ultimatum, I tried to pick it up. Unfortunately, my inventory was full, and the item disappeared as soon as I clicked on it.

Here’s what I’ve tried so far to recover the item:

Reopened the instance and searched my inventory and stash, but the item wasn’t there.
Killed the Chimera again, but no quest item dropped.
Grouped with another player to continue the quest, but there was no progress.
Is there a way to restart the quest?
Or is my character permanently blocked from progressing in the Chaos Trials?

Thank you for your help

You don't happen to be a Titan and the key is in that extra inventory? Happened to me once ngl. :D