If you are seeing the "no visible assets" message please click on your XOGO playlist and ensure that your assets are set to visible. At least some of your assets must be visible, otherwise nothing can play on screen. You will know that your assets are set to visible if you can see the eye icon (videos) or the duration (graphics, dynamic content).
Next, click on schedule next to each asset in your playlist and make sure that you have at least some content scheduled to play everyday. If your assets are visible but not scheduled to play, you will still see the "no visible assets" message.