iOS Game Center achievements are resetting

Question

We have some problems with achievements which were unlocked in Game Center. This is our first time that we implemented Game Center features inside our app and it seems that leaderboards, score reporting and unlocking achievements are all working fine.

• We can see unlocked achievements in the achievements board but they are becoming locked again just a few seconds later. Everything seem to be working fine except this weird behavior (all handlers are returning success etc.)

• Tried many tests with different type of achievements (both with achievable more than once YES and NO achievements). It may be an expected behavior with achievements which are of kind achievable more than once but they are becoming locked again if they are not as such)

As the only thing that comes to our minds: the version with achievements and leaderboard is not published yet in AppStore and we are testing achievements with some sandbox testers and a real user device. Could such resetting (becoming locked again) be due to not yet being published in store?

Thanks in advance for very appreciated tries, help and assistance

If it will help you guide us:

• GKAchievementDescription loadAchievementDescriptionsWithCompletionHandler: returns all achievement registered in appstore connect
• GKAchievement reportAchievements: always return success (and so we can see them in gamecenter board)
• GKAchievement loadAchievementsWithCompletionHandler: returns completed achievements until that reset occurs (i.e. after completing the achievement, we send a request -> it is there; a few seconds later again we send a request -> it is again there; a few more tries and it is gone ...)