Have you tried getting a little closer to the nomads?
Sometimes speech options only show up when you're close to something else. I just played this yesterday but don't remember having any issues with this.
Try walking around a bit or possibly going away some distance, then approaching them again.
I had this issue on PS4 but i just reloaded the automatic save there and it worked.When I arrive on site, I'm supposed to intervene in the discussion before Panam and V go in the tower. But nothing happens when I need to "Discuss the plan with the nomads". Anyone else had the issue, or know how to fix it ?