Try on your existing save first. If it doesn't happen there, you know it was your mods. If it does work, also test a new save :D
I tested issue with my game on vanilla. I moved mods folder out and did as you said. I then tested with both my saved game and then a new game and I can confirm that the mission still does not happen in either case. Pics of the new game below. This time only one of the NPC's walked away after a bit. The other one just stayed there playing with her data pad. I gave up after another 2 sim-hours of them just standing there. The action queue still showed "wait" the whole time. It was very clear that the mission was stuck!
I found a similar issue with the Millennium Falcon outside of doing this mission. If you choose "Explore" it works fine, but if you choose to "Explore with", both Sims just stand there with the same "wait" in the action queue. And this is with both my playing Sims, not NPC's. I noticed this problem early on when I first started with Batuu. So now after this mission problem testing, I put my game back to 'flavored' and then decided to try to "Explore with" and it worked.. just this one time. Then the next time I tried to "Explore with" it no longer worked. The sims were just stuck like before. Also, I made sure both sims were able to "Explore" as in, after their cooldown period expired, so I was able to rule that out as a problem to this. Then I decided to bring my game back to vanilla again and yes the sims are still stuck. They will NOT explore together. So I figured out a possible clue to this problem now. I did notice the one time it did work, there were two things went into the action queue.. "explore" and "wait". I'm not sure if that appeared in both sims queues but I'm certain it did in the sim that chose "explore with". Now when it doesn't work anymore, I looked and noticed only one thing appears in both sims queues, and that is the "wait". "Explore" never appears. Maybe both these glitches are related. It doesn't seem to be just an NPC problem but really a multi-sim problem. You can't "Explore with" in the X-Wing so I can't test that. But like I said before, the X-Wing missions that needed an NPC worked just fine when I played it, so the official fix on that is good for me.
