okay, so in halo 4 there is an achievement called “Dedicated to Crimson” it says to get it you need to do the following “Complete all chapters in the first 5 episodes of Spartan Ops on any difficulty.” key words in that ANY DIFFICULTY. Now. I’ve completed every episode on Normal. a few on heroic with other people, I would like to know why I haven’t got that achievement because it says ANY DIFFICULTY not heroic or harder and I’ve completed every single one. 
it’s the last achievement I need and I’ve done all the required things for it so why haven’t I got it. PLEASE EXPLAIN
Did you complete ALL of them on co-op, or just some?
If so, you can’t have a mix, you have to complete them ALL solo or ALL co-op.