I am not using an Arrpegiator.

When I look at the MIDI Monitor file generated when running BIAB 2014 (which is the last version I have that works properly with the Casio) there are only entries labeled "Ext" in the column for the Source. Looking at the BIAB 2024 MIDI Monitor there are entries for both "Ext" an "1" - what is the difference between source labeled "Ext" and "1" ? I wonder if the fact that source "1" does not show up in the MIDI monitor of the 2014 version has any bearing on the situation. Also, there are no "Note-Off" entries in the 2014 version MIDI monitor file so I don't think that has anything to do with it. In addition, the 2014 file does not have any of the "#88 Undefined" entries that are being generated in the 2024 MIDI monitor file. More clues perhaps?