Adding new staff to existing instrument does not appear in linked part
1. Create new score with several instruments.
2. Go to File -> Parts, choose "New All."
3. Go to Edit -> Instruments, click one of the existing instruments on the right, choose "Add Staff."
4. Close Instruments window. Go to the part for the instrument you added a staff to.
Expected result: the staff will be present in the part. Actual result: it's not there.