Hi, thank you for your bug report!

So, there are 4 possible reasons I can come up with right away, but it really depends on what game you are referring to specifically.

1. The achievement was unlocked "offline", meaning, MGS nor the platform the game is on knows for sure when the achievement was unlocked. If that's the case, MGS will set the unlock time to the time the achievement scan was performed. An example of what that would look like can be seen here; Unknown unlock date set to scan date.


2. The platform the game is on had a temporary issue with saving achievement data. This is rarely platform-wide, so most likely an issue with the game itself. It could have been caused by a temporary network disconnect, and the achievement was not recognized of being unlocked until some hours later when a connection was re-established.


3. The date shown here is in a different time-zone from yours. You can find out if this is the cause of the mismatch by checking your time-zone on your profile page. (You can access this by clicking "Edit Social Networks" on your profile page)


4. The platform has not standardized the unlock time. Whenever an achievement is unlocked, the unlock time is taken from the player's PC-clock, without taking their timezone into account. What happens then is MGS takes that time at face value and apply your timezone set on your profile page.


That's what came to mind right now. I hope this was helpful, but if you would want us to investigate it further, we would need to know what game and achievement(s) in particular is affected as well as your timezone and estimated unlock time. We would also like to know if this is a normal occurrence, or if this is a new behaviour.