Hey guys I don't know if this will help anyone but I was having the same issue and I was able to fix it. I play grounded on PC game pass and ran into the issue of saves not loading, endless processing circle, and then showing no saves at all or even being able to save in singleplayer and multiplayer when making a new game. I tried everything like reinstalling, repairing files, and even restarting my PC. The only thing that did something and fixed my issue was literally disconnecting and reconnecting my internet on my PC. I did it once when I was outside the game and noticed a change once I was in the game but it was still broken. So while still at the save loading screen I then disconnected and reconnected the internet again and the game completely froze and crashed so I had to close and reopen but this time everything fixed itself. I hope this helps someone and I would say just keep messing with it since it may be tied to internet.