Thanks for that but this was me and 3 friends and there were no alarm beacons, We tried all being together, we tried all splitting up, we tried 2 groups of 2, we tried constantly moving around. Interestingly when it was only myself and 1 friend we had no issue with these missions. We had 12 stages in a row of just "kill x" and no problems until invited the other two. Either way it's ridiculous. I've also tried to farm toroids with 1 other, everything was going great before suddenly everything stops spawning and we start losing a wanted level, then another and another. Then we find a few mobs, get the first level andddddddd nothing spawns. So please don't defend this broken junk. Should be like GTA where you get a few stars and can't shake them even if you wanted to!
If you want another good example of terrible spawn rates/mechanics just go solo farm for cryotic... I have to run 150m+ away just to have something spawn at my extractor, at which point i leg it back to find 1 little gunner trying to take it out. I've sat at an extractor for over 3 minutes while I went and made a cup of tea, got back and guess what, both myself and the extractor were fine.
Edit: If you'd read my post properly you'd also have noticed we had no shortage of mobs to kill for the example I gave (We have seen everything though as explained above). We had drop ship after drop ship, blue pillar after blue pillar, the drones simply weren't spawning.