I haven't been able to save any Sandbox games for the last week or so on the PS5. 

When I start a new Sandbox, whether I save straight away or play for a while, the saves aren't saving. The Save icon appears at the top of the screen after each month and when I select Quick Save, but when I go to Exit To Menu I get the messsage:

Do you want to save before quitting to menu? Last saved at 1/1/0001 12:00 AM

Whether i choose Save & Quit or Quit without Saving, when I go back to the Sandbox menu, I get:

Corrupt Sandbox Save Detected

A corrupt Sandbox save file was found in Slot 9, this save file will be ignored. You can overwrite this save file by creating a new save in this slot.

When I hover over the saves, it says:

Loading Sandbox Failed

Loading your sandbox failed.  We're sorry.  File is corrupt

I can open existing saves and save them after continuing playing, but no new saves can be started.

I have tried deleting the game from my console and reinstalling, I have logged out of my TPC account, I have turned off mods, but nothing has fixed it. The same thing is happening for all slots.

Help please!