I'm usually put off if there's any cipher hacking involved, either because someone ran ahead and set alarms off too early, or I get matched with people who aren't aware they're being timed. Since I have barely any friends on Warframe yet, public is my only choice, and more often than not, I feel under pressure before I even start the mission just because of the things I've put up with in the past, or the things I'm expecting to happen. I'm not perfect either, I suck at ciphers and anything stealth related. That feeling of letting a group of 3 people down is disheartening, and another big part of why I don't attempt Sorties if they involve a spy or rescue.

TL;DR: 2 nervous and dont wanna let ppl down
also pub squads sometimes arent the best but that is to be expected since everyone has their own struggles