When you load a project,SONAR checks to see if the exact same output ports are assigned as when the project was saved.SONAR’s port assignments can change if you load the project on a different hardware configuration or change driver models.If there is any discrepancy between the port assignments that were saved and the ports that are used in the current configuration,the ports are set to “None” and the Silent Buses Detected dialog displays all track and bus outputs from the current project that have been assigned to a silent output.
The Silent Buses Detected dialog also appears if any track or bus output is assigned to “None” as a result of changing the audio configuration.