Sorry to insist on this, but I'm still having the same problem. I've managed to get the "Meteor shower!" moodlet several times but no actual meteor shower happens.
Stranger still, my sim's child has the school opportunity to collect gems and metals, so when I control her, I can go to world view and see gems and metals spawners. Well... the lot I have the Group Science Project machine is plagued with spawners, but if I close up, the gems and metals aren't there. I went into buy mode and they aren't there either, not even with buydebug enabled. Reseting the world didn't fix it and I have no idea what to do or why this is happening.
I have placed the machine on a residential lot (an extra one, not where my sims live), on an empty island and surrounded by fence to keep curiuos sims away from it. Could this have something to do with it? I tried turning the lot to Community but the whole neighborhood decided to check it out and I couldn't get my sim to trigger the meteor shower with all the other sims messing up with the machine.
Please, help!