I beat the Halo 4 campaign on Legendary, Solo. Only used the skulls Grunt Birthday Party and IWHBYD. No matter what I try to do, it does not give me the achievement for beating the Halo 4 campaign at all.
I've tried playing each mission over again, mainly Midnight. No matter what I try, it absolutely refuses to give me the achievements. I'm missing the achievements for beating Midnight, beating the par score on Midnight, beating the campaign on Easy, beating the campaign on Normal, beating the campaign on Heroic, beating the campaign on Legendary, and beating the campaign on Legendary alone.
I'm tired of retrying each and every mission. I've asked and asked and asked people why it won't work. I'm trying to be as cooperative as possible. I'd really prefer if I just got the achievements instead of someone giving me a "trick" on what mission to play, but any assistance at all is much appreciated.