The AI is so bad(squad especially) that it can end your mission over and over, without fault of your own(the campaign is terrible for for this)
Thats one of the things which annoyed me on one of the missions, one of my squad died and it did that annoying thing that sometimes occurs in games where I failed the mission because one of my squad died. Big deal ! Its war! People die, the loss of one soldier hardly designates a mission failure for goodness sake. I still had everyone else left, more than enough people to continue and succeed in my objectives, acceptable losses, but nooooo....
I'm hoping it was just that particular mission though.