Ritual challege with 4 bosses - unable to complete

Been doing challanges with this guide: [Removed by Support]
I've catched 5 bosses in 4 vessels
https://imgur.com/a/pFmy3FW
Opened a map with them and successfully cleared all 4 rituals without dying, but this challange hasn't completed.
What i've done wrong?

Bug report number: 1 381 607 474

Easy way to do it is add a bunch of exiles on the map as they count as unique's. I did it in the Precint map, don't think I even had any extra exiles added, just got the altar in the boss room.

Find a map that naturally has more than 1 boss. Roll the Twinned modifier on it. As long as the altar spawns in the boss area so you can kill these bosses, you are good.

You cannot do this challenge with vessels.

Iceberg has 4 bosses by default since you are fighting a Warband boss and the adds, all of them do count for the challenge

Thank you all, but i don't understand why i unable to complete it with my setup? 4 vessels, 5 bosses, all killed.

because the description or the background conditions are wrong OP, I tried to do it your way too I had 7 bosses captured I think and i didn't get completion.

Just run precinct with ritual on, soon as you random 4 exiles as the boss you'll get it complete it was pretty quick. Treat the challenge as "capture 4 bosses in one ritual" rather than w/e it says at the moment.