Using a renderer in Songcast mode does not work with BubbleUPnP.
Steps to reproduce:
1. Switching a renderers source from "Playlist" to "PL-to-Songcast".
2. Select this renderer in BubblePnP.
3. Select a track or playlist from the library to play to.
4. BubbleUPnP tells the renderer to switch its source from "PL-to-Songcast" to "Playlist".