If you run Guided Search version 11.3.0 or later versions in Chrome version 62, Mozilla Firefox 60 ESR, or later, you will be prompted to install the latest version of Flash when you open an editor in Experience Manager.

Click the link to install. You will then be prompted to indicate whether you want to allow or block Flash. Click Allow, and then Click on "Run Flash this time" in the blocked plugin icon in the address bar.