Well, not really. I was playing Crackdown 2 and decided to finally track down and bag all the Hidden Orbs. After a few hours me and my buddy get the last one and the achievements pop. One for getting all the Hidden Orbs and another for getting ALL the orbs in the game. 1000G. 
 
However, my friend told me Sixth Sense (Hidden Orbs) isn't shown as unlocked for me, so I checked Xbox.com, and guess what? It says it's locked too. 
 
 This sucks, lol. Anyone know a way to fix this?

The only other way is to restart the game. I know, it's a shit load of work, but that's how Achievements and trophies work. I remember when I tried getting the million and billion dollar trophy for Mercenaries 2. Apparently, if you go past the million and billion dollar mark and the server doesn't register it, then you're fucked. Meaning you will never get it because the EA server goes by your PSN ID. 

Yeah, but it is unlocked for me. I can't reset that.

You don't understand the definition of the word scam.

Yeah. Me and my friend did co-op Gears of War on insane, and after we beat it we noticed he didn't get any of the achievements, and I did.

" @CL60: Did he have them unlocked on his console, though? It's just on xbox.com and if people compare their games to me that it doesn't show. "

So it is just not showing on Xbox.com, but it is on your console? My guess is maybe Xbox.com is not updating properly and has not noticed you unlocked the achievement. How long ago did you unlock it?

" @supermike6: Sorry, you don't understand sarcasm. "

My friend is chasing my score and winning all of a sudden. I usually play offline, but my score is accurate. Anyway he messages me online saying he beat me by one point, and I tell him he did not because it did not update. If it updated on your console/gamer tag, than you just need to log into xbox live and give it a bit before it updates. As long as your gamer score appears accurate online to others who cares if they don't see it in compared games?
 
Anyway make sure you go online at least one and than sleep on it....

Yeh, I'd say give the website a bit of time and see if it changes.

" @JuanSolid:  @Damien: Yeah, I'm assuming the same thing. It's probably happened a ton of times, but obviously I've not gone to check Xbox.com to see if it's updated before. 
 
If it isn't fixed within 24hrs, I'll try recovering my profile and see if I can redo it. 
 
Link to profile. "