Re: Why that's the keystone? mission has gone
@aodoherty The one time I had that mission, the same thing happened to me: my sims had traveled to France and retrieved the keystone, but the mission dropped when they arrived in China. My sim found the mission on the adventure board right away though, and completed it while on that China trip. I think it's just kind of borked in that it drops when your sims arrive in China.
Is there a reason your sims can't find the mission again and then start working on it right away? That should be fine. If you don't see it on the adventure board on day one, try doing a couple of easy missions first, or even assigning a mission and dropping it to refresh the options. (This only works some of the time.) Other than that, you can assign the mission with a mod whenever your sims are ready.