There is a current outage affecting all Xbox One achievements, all games, beyond the usual issue of some achievements reaching 100% yet not unlocking. See the XBL Status page.
> 7/31/2014 12:29:12 PM CST:
>
> It’s come to our attention that some of you are having a tough time posting statistics to leaderboards and unlocking achievements on Xbox One. We also know that some of you are seeing a black screen when attempting to launch games or applications on Xbox 360. Hang in there, Xbox members, we’re on it! Thanks for your patience while we work to resolve these issues. We’ll update you again as soon as we have more information.
Just wanted to let everyone know since there have been many postings about this is the Spartan Assault forum.
Edit: The XBL Service Status page now says the Xbox One achievement issue is fixed.
> 7/31/2014 4:38:39 PM CST:
>
> Xbox members, were you unable to post statistics to leaderboards and unlock achievements on Xbox One? We fixed the issue! Meanwhile, we know some of you are seeing a black screen when attempting to launch games and applications on Xbox 360. Hang in there, we’re working hard to fix the black-screen issue. Thanks for your patience during this process. We’ll update you again when we have more information.
Mods, please lock this thread.
