Dorico MIDI export includes an extra low note?

I’ve been having this issue that an extra note (C0) was included when export MIDI from a dorico file. This note is sustained for a long time through many measures. It appears when I import it into Cubase as well as in Yamaha Song_to_Style converter. When it appears in Yamaha Song_to_Style converted, it means it wasn’t caused by Cubase. This note is invisible in Dorico staves.
I ended up using Midi editor to manually remove it.
Is this a bug in Dorico 5 ?
Thx
Quang

It’s a keyswitch. It tells the VST to play a different sound. See this thread for advice.