Quest \ "Final Crucible \" (Stellaris)

In the second stage of the quest, you need to find the ships of the cultists in the Uldor system. When I found them, I didn't have the strength to win, so I decided to save up my strength and come back later. The problem is that when I returned to bend them, there was no one in the system, although the marker still points to it! Was there something like that for someone?