After I upgraded to 3.5 on a new install of WordPress (plugin-free). I am no longer able to edit themes in the theme editor.
I will make changes in the CSS file and save. It will "think about it" for a second, as though it is going to update my file but then the file changes back to the original stylesheet and doesn't save my changes.
I am trying to edit the twenty twelve theme.
Any help would be much appreciated!