HELP: Cubase 10.5 or Halion SE3 or Olympic Choir Issue

I need some help please from more experienced folk than I. This is driving me bonkers!

Set-Up

Win10 (64-bit)
Cubase Pro 10.5.30 (build 16 Feb 2021)
Halion SE 3.4.20.139
Olympus Elements
Patch: Legato mm Ch2
The Grand 3
Patch: Yamaha C7 Close Ch1
MOTIF XS80

MIDI Thru is managed by Cubase and turned off on the MOTIF.

Two MIDI tracks in the project; one for Piano (Ch1) and one for Choir (Ch2). Both instruments set as RACK instruments.

The MOTIF is set as the MIDI IN to Cubase (all).

Issue

Playing any note on the Olympus Choir causes a D3 to cypher as soon as the key is lifted. The only way to stop it is with a MIDI Reset either from Cubase or Halion.

This does not happen with any other publisher’s Halion patches nor any other virtual instrument. In particular it doesn’t happen with The Grand in the same project (even if I swap MIDI channels).

A MIDI monitor INSERTed in the Halion channel correctly shows both the NOTE ON event and the NOTE OFF event (actually a NOTE ON 0 from the MOTIF) both at the correct pitch. As soon as the NOTE ON 0 is sent by releasing the played key on the MOTIF, Halion starts playing D3 (irrespective of the original note played on the MOTIF) but no MIDI event shows as having been sent through the MIDI monitor.

Help Needed

I’ve spent hours now looking through the preferences, channel settings and so on in Cubase and Halion and can find nothing that triggers this NOTE ON D3 event. I’ve had MIDI monitors on the output of the MOTIF (no D3 NOTE ON), I can see no events like this when I record a track (and yet the D3 note still cyphers on play-back)

Similarly, I’ve been through pretty much every parameter in Olympus Choir and can find nothing that I understand able to create this NOTE ON D3 “ghost” event.

  1. Am I doing something wrong?
  2. Am I alone?
  3. Where should I be looking to correct this massive problem?

The Olympus Choir is a truly awesome instrument but at the moment unusable unless I want to compose something with a D3 choral drone starting as the first “mm” stops.

Jamie