I wonder if someone has encountered this before… Whenever i change something trivial in the score editor (say change a note pitch note) and then try to undo that the score editor closes. It does happen in a specific project continuously (the one that is mos important of course) but other projects seem to be okay. Any Ideas for a workaround or solution/cause ? Score editor closes in lower pane as wel as in full editor mode. Cubase 10.040, Windows
Sounds like corrupt prefs. Do a Cubase Safe Start to test.
Hi Steve, thanks for your reply.
I’ve found the cause, it seems to be a bug in Cubase though, safe start didn’t do the trick (in any of the safe starting modes), but it somehow rebooted my mindset also 
Anyways here is the behavior I noticed.
Having a chord track and the chords shown in a midi piano track score page-layout I noticed that when I thought I was just graphically laying-out the chords they where actually moving song positions in the chord track (and the vertical layout changes are recorded in the project layer - but that’s a different story).
So did put a “Lock” on the chord track to see if that would force the chords to stick to their song position (it did not, but never mind)
note: The piano track does not do anything with the chords (it does not follow them or what so ever) it just displays them in the score part.
Now: When you have placed a lock on the chord track present: Undoing any note editing in de score editor will cause the score editor to close. Also the score editors of tracks that do not display chords at all. I have not noticed this in previous versions of Cubase.
Releasing the lock on the chord track will turn everything to behave normal again.
Regards,
Hans