Death during boss fight on delirum map reset the map

This is the 2nd time this has happened. This time it was on a map called digsite. I was fighting the delirum boss - who was empowered by a azmeri spirit - and I died (for being dumb).

Regardless, when I respawned the delirium was gone, no items, no monsters, only the boss.

This is a feature. If you die in a boss fight, you can revive but the rest of the map is empty. I forget where but this is how it's designed.