Niko. Quest bug after death.

During the very first Delve quest (collect azurite for Niko), I died before collecting the azurite. Since then, Niko no longer appears on maps, I can't collect more sulphite, and in the Mine Encampment, all Delve nodes are empty - no monsters, no azurite, and the crawler does not move (it just spawns directly at the destination node). I also cannot see any azurite in the walls.

I can enter Delve, I can move through the labyrinths, but the quest (collect Azurite 0/30) is hanging open. And I suspect that Nico will not appear on the map because of this and will not offer me to find some more Sulfurite (I ran through the mines several times in Act 4 in the hope of this).