So I just finished the last episode of the first 5 and I didn’t receive the Dedicated to Crimson achievement. Looking through my list of episodes it no longer shows that I finished anything in episode 2 but when I go down to each chapter in episode it shows that I have completed them all on legendary. I also never received my email for the armor specializations so I’m not have a lot of luck with Halo 4 so far.
Just replay any episode 5 chapter solo and the achievement will pop.