Here's the bug process on PS4.
Start the game under one of your PlayStation user names.
Create a save file in sandbox mode.
Exit the game.
Switch PlayStation user.
Enter the game.
Try to continue a saved game. There should be no saved data on this PlayStation user name.
While in game hit the PlayStation button and switch back to your original user.
Try to continue a saved game. There should still be no saved data.
Exit the game.
Enter the game.
Saved data is now corrupt.
Doesnt happen every time. Found this when I accidentally started the game under my sons user name. Tried to change users in game but it didn't work to bring up my save files. Exited the game and reentered and all of my saved files were corrupt...hours of space station construction lost.