Item refunds
Epic raid items can be restored in the case of a server crash/roll-back, providing a message is sent to us which fulfills the following conditions:
Exact date of the raid;
Screenshot of the raid ID;
Screenshot of the loot & Full list of raid members;
Name of the player who received the item.
Yes, ID matters.
You don't need to stay in the instance Juju, you can go to bed

If the evidence is sufficient enough, they can assist you, no matter if you're still in there or not.
That said, i'm not sure if this is something they can assist with, as there was no loot. Maybe they could grant you a free kill for loot since you have proof of killing it.
Best of luck with this matter anyhow.