This is often caused by a combination of two settings.   1. Always Echo Current MIDI Track is enabled (the default). As a result, inputs set to None are automatically switched to "All Tracks > Omni" when the track is given focus. Instead of not listen for any MIDI data, the tracks are receiving all MIDI data coming from anywhere. Turning this option off in preferences and setting inputs to specific MIDI sources (such as a controller) are the solution. This has been the subject of a