I have a Montage M8x and am working with Reaper.  I am attempting to setup some backing tracks but having difficulty getting Reaper and Montage to work together.  My goal is to setup multiple tracks to play through the Montage via their own MIDI channels.  I have Reaper setup to output a track to a specific MIDI channel but Montage is not behaving as expected.

If I send MIDI via a channel that does not have a part in the currently active performance, a new part is created with the respective part number and assigned an instrument called "Piano Vintage".  MIDI playback works through this as long as nothing is changed.  But if I change the instrument to anything else, Montage refuses to acknowledge or play back any MIDI notes.  The only way to get it working again is to delete the part and let it get automatically created again upon the next playback.

My first thought was that there's something funky in the MIDI control events from Reaper.  But I can wait until mid-playback and change the instrument in (when only notes are being sent) and the Montage will stop playing and all activity on the part's level indicator ceases.  Any thoughts on why the Montage refuses to play any MIDI notes received in this scenario?