Can you please try this repro?
New empty project
- create Five midi tracks, name them Violin, Violin 2, Viola, Cello, Bass (Note that Cubase will automaitaclly select Bass Singer, not double bass, but this is fine for our purpose.
- create midi parts on each track (let’s say 32 bars)
- open the Score Editor on a second Screen
- open the Key Editor in a window on different screen
- in the key editor activate Global Tracks to see the midi parts
- Close the Score Editor
- repeatedly select and deselect the parts in the global view of the Key Editor
- now, add a note or two to each part
- Open the Score Editor
Have any of the instruments changed?
Here, Cello got switched to Bass Singer
@mducharme