Some of achievements didn’t add up to my gamerscore

That didn’t work unfortunately. Still falsely showing the achievement as locked and my gamerscore hasn’t updated either.

Getting all the achievements in Ark. Didn’t personally have interest in playing it, but good for padding out my gamerscore.

This sounds like my issue.

Some achievements on the XBox One are just not adding to my total gamerscore. It's rather strange, since some achievements do add to my total gamerscore, and it shows that I have all the correct achievements in the individual games.

My total GS is 75 points less than what it should be at the moment.

mines the same. since the new website some of my achievements are missing... the gamerscores right but some of the achievements used to get the score are still blank when i aquired them a long time ago. LA noire for example, i got these achievements months
ago and some are now missing. this is only on the website. the gamerscore is correct but it doesnt show all the achievements that add up to the gamerscore. same with my friends on xbox.com. for example, it says my friend completed the campaign on MW3, it shows
the achievement for that, but its not showing that he aquired the achievement for completing the first and second missions. we all know this is impossible as he would have to have these to complete the campaign lol. i think its an error with the new website.

I sort of had this problem after I changed my gamertag. I redownloaded my profile after that, and I was short by about 900+ gamerscore (all my Xbox One achievements) on my 360. But they eventually showed back up after I got some more achievements on my One.
I haven't had any issues since. Seems like it just takes a little waiting for it to add back up.