Game Center/ Apple ID

Hello 👋

I have had a problem for quite a while. Playing a game called Hill climb2. I have an iPhone and an iPad for connecting and save progress. The problem is that only my phone will connect to the Game Center for saving progress. Not my iPad. They are linked with the same id and and everything seems fine until I try to load progress inside the game. It will not log in with Game Center, even if it comes a pop up saying I’m logged in. Neither devices log in to ID thought. Only my phone - Game Center. I’ve tried to factory reset the iPad. Logged out and in again to Game Center in settings. By now I’m exhausted. Months trying and trying. Please help 🙏