1.1 R4902 Score tabs disappear
If you have MS set to "Continue Last Session" under prefs, and you have more than one score open, and you leave anything but the first score tab as the active score when you quit, then the next time you start MS no score tabs will be visible, the entire line will be gone. Closing a score (Ctrl-F4) or open another one will correct this. Ctrl-Tab to cycle through the scores won't work.
This is MS with 3 scores open before I quit. Note the third score was active:
This is MS after a restart, still 3 scores but there's no tabbed bar anymore. The third score is the active one still.