I recently added a GameCenter Leaderboard to my very simple SpriteKit game, and while it worked initially, when I put the game on Test Flight and it was tested on an actual device, it wasn't logging high scores.
Then when I tested it again in the simulator, I found it was no longer logging highest scores there either.
After a lot of Googling and I've found that a) there aren't many questions or tutorials out there about Game Kit that have been posted recently (2017), and b) a lot of people mentioned bugs and issues with GameKit that seemed to get fixed on a case by case situation ... either by contacting Apple about a live game, or GameCenter just magically started to log high scores again.
I know that Apple have taken out the Game Center App as of iOS10, and while documentation suggests Game Center functions (such as Leaderboard) are still supported (and iTunes Connect allows you to create them), I'm just wondering if anyone has any experience or knowledge of whether the issues are connected to Apple phasing out Game Center?