I got this in my previous game. When I searched for the missing colonists, I found them and got a result that should have finished it. It didn't. The project continued to appear for the rest of the game, but nothing happened when I did it again. There must be a bug that allows the project to keep being available when there is nothing for it to do.
I also got this several versions ago and it didn't work right at all. I think it depends on some of the choices that are made as the event progresses.
You should ignore it.