Is this behavior the same in Cubase 6? I found this in Mac Cubase 5.5.2
Create midi track and part in new project.
Open Score edit.
Create the chord spelled ‘Cmin’ using the pencil tool and typing into the text fields of the Edit Chord Symbol window. (e.g., not using the chord type drop down)
You now have this chord: ‘Cmin’
Close score edit
open list edit and look at the chord event, it has changed
Open score edit, the chord is now spelled differently: it is now ‘C-’
How the chord depends on what the chord was originally, and some other stuff, but I could not decipher what. Going to Chord Settings>Chord Symbols and clicking Apply to Chords fixes this particular case, but does not in other cases.
edited for clarity…