Xbox Live achievements randomly disappear

Check http://enforcement.xbox.com to make sure you haven't been given a gamerscore reset. If not, then it's just a glitch that will fix itself.

If it is a gamerscore reset how come my achievements for that game still say 48/48 why not put it to 0/0.

That's why it's more likely a glitch than a reset.

Check http://enforcement.xbox.com to make sure you haven't been given a gamerscore reset. If not, then it's just a glitch that will fix itself.

Thanks for replying StarKi113R13, and forgive me if I lost my temper a bit in the first post.

I tried restoring my Xbox One to its factory setting including installing all updates, but I'm afraid that didn't work. The wrongly add achievements are still showing up both on the console and on Xbox.com. I'm suspecting this may be a problem with my account
itself. I'll be sure to reset my password and check my security information in due time, but to be honest, I'm feeling quite hopeless at the moment.

Are there any other solutions that I could try?

Oh, good! Glad we got your First Blood unlocked for you! It will look a little odd, but I promise that it all looks legit on our side. And if it comes down to it, you have this thread to prove that I had you do troubleshooting steps that caused that.

As for the other achievements, I mean the first way you explained. It should show the progress, along with the timestamp. This will help me get a clear picture as to what is going on.