can't go to endgame/softlock

i finished all acts and interludes, but on the final bosses(vaal shelter) i died after killing them. i go back from the checkpoint, but the battle doesn't started. i call doriani from the dark orb. He come, said his monologue and then nothing. I think, that i must defeat them again, restart location, but it doesn't work. Please, help

You need to go to a new instance of the area (Ctrl+Click on Waypoint or wait at least 15 minutes outside of the area), so that the boss reappears.