Time Gates: The objectives had a 48 hour countdown. We needed to fill the bar up before the Automaton bar filled up. This timegated race concept is fine in theory, but it quickly grows to be an issue due to the following.
Mission Type: Every operation on defense campaign planets included civilian evacuation. It's not a great mission type as is. But guaranteeing at least 1 mission will involve it quickly turned people off from touching it. Higher difficulties sometimes involved 2, with one being a variant of it.
Difficulty Issues: Aforementioned mission type had a bug for a few days into the order where the resistance mounted against you would be higher than that of the difficulty you had selected. If you felt you could confidently do challenging, you were going to get a far more difficult experience.
Reward: 12,500 requisition slips iirc. Our first major order gave us 10,000. Not bad if given at or a few days after launch. But the time gates guaranteed it'd be at least 16 days after the first major order ended. Problem here is that people were quickly making that much from missions alone. Then if by some chance you reached at least level 20 and also bought all the stratagems you could, this reward had little value to you. It had even less if you hit the current cap of 50,000 req slips.
So ultimately, each objective was a 48 hour race to fill up a bar, that could only be contributed to by playing a mission type nobody was really enjoying, and had been bugged for an early portion of the order, all for a reward that may or may not even be worth it by this point. Very quickly players decided they just didn't want to do this. I'd say it's part of why Malevelon Creek became such a meme. "Space Vietnam" is just one sector over, and it was relevant since it was against the Automatons.
We cleared the recent Terminid order very quickly, and are on track to clear the current Terminid order because players can actively contribute and in a variety of ways. But even the current order highlights that Time Gates with some contexts are just a bit silly. We currently have both planets liberated and are now just sitting around on our hands just going after whatever planets are close to liberation.
Foundationally it just wasn't a good order. Here's hoping they learned from that one and be thankful it was early on in the lifespan of the game.