I don’t have a way of monitoring the 3.5mm MIDI on the Flat V so I don’t know for sure that the Poly was responding to the Sysex messages, just that the ML10X message seemed to have something to do with it. I was suspecting it was an issue with the Poly but I’ve heard Poly support is pretty slow/unresponsive and figured creative programming could be a fix. I’ll add info here if I hear back.
Thanks for the great products and design that allow me to find my own solution!