Since this is an experimental support, some graphical elements might be missing from the rendered image.
The CGM rendering support is based on a third party library. In its free of charge variant it renders the images watermarked with the string Demo, painted across the panel. You can find more information about ordering the fully functioning version here: http://www.bdaum.de/cgmpanel.htm.
Follow this procedure to enable the rendering of CGM images in Author mode: