I have an instrument track using Presence that stopped playing midi notes. It had been working OK for a few days, but for unknown reasons it stopped making sound. I could edit it and directly play Presence and hear audio, but the notes would not create audio on playback. As a workaround, I copied the midi info into a new instrument track configured the same way for Presence and it worked OK. However, now I cannot delete the original midi track. The track appears in the Mix view, but not in the arranger view. The track does appear in the Track List view. When I select the track in Mix or Track List view and use Track menu to try Remove Track, the Remove Track button is grayed out. So I have an empty track (actually, now two of them) that do nothing but cannot be deleted. Studio One 4 Pro, 126.96.36.1999941 Build Oct 30 2018.