So, last night I was playing Destiny and during my session I got 3 achievements for Halo: MCC. The achievements said they were unlocked on 11-11-14 but I just got the notification last night. Achievements are "Sacred Icon", "Delta Halo", and "So you don't want the tank". Has anyone else experienced something like this? I haven't played Halo: MCC in two days.
Me too man! I was going to make a post about this, this morning. I was watching South Park on Hulu Plus, and I got all my locked (but completed) achievements
I just turned on my xbox just to find 10+ notifications about MCC achievys I got. Like finally says I beat halo 1 campaign. now just waiting on my H2 ahcievs to unlock
Lots of players have been reporting that their stuck achievements have been unlocking... Mine all unlocked a few days ago. Think it has something to do with the 7 December update.
I'm trying to think how the achievement system works and how it would take days for achievements to unlock after the patch. The only thing I can think of is similar to a traffic jam. Everyone's data goes to a system that inspects it for doing something to earn an achievement. A wreck (or in this case some sort of hang up in the code) causes all traffic to stop and it isn't until it is clear that the traffic flows again. But depending on where your car is in the jam, you might not be free for quite some time.
Now apply that to thousands of people getting hundreds of achievements all at the same time.

I don't know how the achievement system works, but my theory makes sense.
Or maybe the game is just more broken than I originally thought (which would be terrible).
it's confusing
Lots of players have been reporting that their stuck achievements have been unlocking... Mine all unlocked a few days ago. Think it has something to do with the 7 December update.
Actually, I'm 99.9% sure that this was never 343i's issue to start with. My theory as to the "Done! Unlocking..." achievements can be found here.

I hope you all find this helpful. I have a feeling we'll be seeing something similar at the launch of Halo 5: Guardians.
Me too! I was watching tv last night and for about 2 hours I had an achievement unlock for MCC. I had 8 that were stuck unlocking and they all cam through. So awesome! Some of the achievements were from as long as 23 days ago lol. Not sure whether it was 343i or microsoft who had the problem but I will take it. Finally some good news with the game.
Looks like HMCC is having a really bad time with achievements. I have at least 5 achievements in a state of "Done! Unlocking..." for about a month.
Some achievements just dont work, a lost count how many stages I have completed (some more than one), and simply didnt get the achievement.
And the same goes to completing a campaign achievements, in HCE, H2 and H4, they are all broken. I dont finished the 3, so...
Some achievements pop, even if I dont have meet the requirements. And they can unlock anytime, doesnt matter if Im playing Halo or watching the Youtube.

I bet 343 will fix that the same way they fix Halo 4 achievements; a year from now they will release an update, and when you open the game they will all unlock at once. Doesnt matter if you deserve it or not. Thats the way they "fix" things....
I am just glad it is fixed for me and most others.