Yeah that's bizarre, those things are usually a major pain in the ass, one of the missions at Yanov has you killing two of them at once, while they're throwing massive balls of death at you. Also, for the most part, missions don't have time limits in CoP, the only one I can think of off the top of my head is the mission at the creek where you help the loners break up an arms deal between some Bandits and some Mercs at the Forest Authority place, you actually have to go and do that like right away. And a lot of the missions, especially the storyline ones that aren't marked, end up just resolving themselves or changing throughout the game. If something doesn't look doable right now, don't worry about it.