As in update of Mixer manager, failed sources are managed in update of SessionSources. RenderSources that fail are re-created. Attach/Detach/Attached of sources functions is unified between Session and Mixer.
When a source in a session fails, it is not anymore deleted after update; the Mixer keeps it in the session but detaches it from the scene. This way the user can access the failed source in the navigator (listed in RED), and Replace the source. The Replacement of source is available for any source. The source visitor does not skip a visit if the source failed.