It's a bizarre rare bug that occurs for some users, mostly due to the save file somehow corrupting. Go to AppData\Local\AtC_BB\Saved\SaveGames and move or delete the .sav file, start a newgame to create a new save game, quit, replace the new .sav file with your old one if you decided to move it rather than deleting it and it should function properly now. Deleting the .sav usually fixes it more often than trying to replace the new one with the old .sav. Hopefully this helps!