Sometimes, ID gets into a state where the Character Style drop-down list will not drop down. I can click either the list item itself or the little [v] button to its right, nothing happens. If I click it again, the screen will just flash open the list for just an instant, but it will not drop down the list and let me select from it. The only workaround is to use View › Character Styles, which slows me down quite a bit, because I usually leave the View › Paragraph Styles window open.