Losing boss fight due to DoT and unable to redo the fight since game counts it as fight done.

Can we do something about this ridiculous "bug" when we are dying on a boss (for example on Kulemak) and then, he dies due to DoT, drops items that you cannot pick up and then when you respawn back on checkpoint, no items nor possibility to fight him again? Like that is just a huge joke and a slap to the face. I lost time and items, on top of that it cancelled for some reason my map that I was doing so I lost possible few divs of items/currency due to that one freak up bug. GGG DO STH ABOUT THIS. ITS NOT THE FIRST AND MOST LIKELY NOT THE LAST TIME THIS HAPPENS.