On March 3rd 2018, the Nintendo Switch celebrated its first anniversary of going on sale in the UK, and with that came an unexpected bug which caught many players off guard. The Switch keeps track of when you first played a game, and how many hours of that game you have played, but that data seems to be resetting one year after you first play a game. People who picked up a Switch and Breath of the Wild on launch day are seeing their total play time drop to 0 hours, and their first played date moved by a year.
This bug doesn't effect save data or anything, it's just an odd oversight that is causing people to lose a record of how much time they've spent playing games on the system.
Nintendo acknowledged the issue, and promised more information to come in the near future.
Some Nintendo Switch owners’ play activity information is displaying incorrectly. We are aware of the issue and we expect to have more information to share in the near future.
— Nintendo of America (@NintendoAmerica) March 3, 2018
However, folks over at Reddit appear to have already worked out what the root cause of the bug is. According to user Vook64, the Switch appears not to log the year of your first playing the game, just the month and day, meaning after a year it resets to being played for the first time on the new instance of that date.
Looks like Nintendo's code is only looking for the day and month you last played the game and figuring out the time since then. It's ignoring the year.
It doesn't know you started March 3rd 2017, just March 3rd so 0 days ago.
So, there you have it. It's not a huge issue, and maybe Nintendo can fix it soon, but it does mean those brag worthy screenshots of your hundreds of hours in Zelda might unfortunately have vanished while you were looking elsewhere.