Did campaign mission but no achievement?

[Pwning_Waffle]

A few days ago I finished the mission 'Infinity' on Heroic and never got an achievement for it, nor does it say I've completed the mission. Yet, all the missions after it are unlocked. Yes, I was online when I did the mission. I also went back to rally point charlie and did it but still, nothing happened. It seems like a lot of people are getting this problem. Is there a solution? I'm getting really mad at 343

 

Thanks

~Pwning Waffle

[fzdw11]

A few days ago I finished the mission 'Infinity' on Heroic and never got an achievement for it, nor does it say I've completed the mission. Yet, all the missions after it are unlocked. Yes, I was online when I did the mission. I also went back to rally point charlie and did it but still, nothing happened. It seems like a lot of people are getting this problem. Is there a solution? I'm getting really mad at 343

 

Thanks

~Pwning Waffle

 

Make sure all of the missions are marked off as completed for Heroic, including the prologue and the epilogue, also I don't believe a combination of Co-Op and Solo will do it, though I'm not 100% sure on that.

[XnosgothX]

Both me and a friend of mine had some issues with the campaign the first time we played it. We both played it solo on Legendary the first time we played it, and neither of us got the corresponding achievement for finishing the game. When going to our stats, it showed that we each had 1 level that we had apparently not finished. I don't recall if we got the achievement for our respective missing levels, but we both had to play those levels again to get the achievements for finishing the story on Legendary.

 

My suggestion would be, sorry to say, playing the level again from the start, rather than going back to Rally Point Charlie.