Update 4 has implemented many new features, including a new save/load function with multiple saves. This also included a new save folder in "my documents" instead of the old folder. The new save location has caused issues for some players as the game was unable to find or access the folder.
To fix this issue the save location is reverted to the old folder, also meaning that old save-games will be working again.
There are also a few issues with the controller and other features that will be fixed shortly.
Update 4 was an extensive update and bugs / issues have been expected.
The last few days before full release is focused mainly to address all the bugs/issues and if you experience problems, don't hesitate to report them!