May have found an issue here. I have set up and enabled a custom style sheet (still allowing the standard sheet). This works fine until I went to add a group in the admin panel. If I add the group, then click save, then refresh the page, the custom sheet is blown away (shift + refresh doesn’t work either) and the only way to get it back is to go and change something in the sheet (so that the save button is enabled) and then click save. Shift + Refresh then reloads the custom CSS.
Also I would like to add that it would be nice to get some kind of message that the group saved when the save button is clicked.