Noel - Thanks!! you've described it exactly. When I call up a song that has previously had midi tracks, I get something that looks like your 2nd image. I can click on it and the dxi window comes up. It indicates "none" as in no synth patch loaded. If I re-select "none", "Sforzando" goes away from the plug-in list, and my mixer looks like your 3rd image (all "none" in green).

I am running BIAB 2017 and I just installed the latest build (457) yesterday. It has done this for about as long as I have had BIAB on this computer (except the synth was "Sampletank", obviously) and I have upgraded every year since 2013.