What messed you up in the campaign? Whether it was an AI’s atrocious driving, a glitch, or simply user error, post it and what your original goal was.
Once I accidentally drove a gungoose into a wall and it just sunk and sunk and sunk until my game eventually crashed. Then, I was on the elevator section and there’s a hidden Spartan Laser (or an rpg I forgot) and usually an AI will say, for example, Buck’s quote "That’s A beauty! You should take it yourself," if you tell them to pick up an energy sword, turret, etc. So I marked the laser. Someone said the dialogue, but they took it. I pushed them off the ledge. THEY STOLE MY SPARTAN LASER. I wanted it 
for both of these I was just trying to complete the normal campaign for the first time.
I hate how the ai stands right out in the open and continues to do so even if their getting shot, this has happened so many times and its even more annoying on legendary difficulty, the reason is so they don’t die making it 10 times harder for you. (trying to get the achievement for lone wolf and completing it on legendary difficulty.)
I soft-locked by launching too high on The Breaking in the middle of a run with my buds 