I managed to kill 2 of 3 Ultras in cosmodrome, but somehow Stirok, Banner of Oryx is not willing to spawn in the Rocketyard. I watched dozens of videos and guides on how to spawn him but the event keeps on failing (even with a fireteam). Did anyone else experience problems with this quest and maybe found a solution? Anyone willing to join my fireteam and try it ? Hit me up on PS4, Peet_Stranger, Thank you for your time.