Occasionally SongKong can have a problem with it internal database, you can recognise this when you run Fix Songs and SongKong fails to load any songs. You can can recreate the database using Empty Database but if this doesn’t work you will currently have to delete the database manually
OSX:
Close SongKong
From Finder, hold down Option Button and select Go menu
Select Library from the list
Select Preferences : SongKong
Delete Database folder
Restart SongKong
Windows:
Close SongKong
Go to C:\Users\username\Appdata\Roaming\SongKong
Delete Database folder
Restart SongKong