Change instrument automatic features flawed
Create a multi instrument score with piccolo using the standard treble clef as one of the instruments.
Change to flute mid-staff using change instruments text.
Text is changed to flute
Instrument will be changed in staff/part properties to Flute with the default instrument names with nothing else added.
Text is changed to flute (as expected)
Instrument is changed in staff/part properties (as expected)
unnecessary clef is added since piccolo is a transposing instrument (1 octave) and uses same clef as flute though it can be deleted
Unnecessary key signature (since both are C instruments) is added to all staves which cannot be deleted by the user. You can delete the key signature on the piccolo only, but the other key signatures are there until you save and reload the score (this is the only workaround I'm aware of).
Note: I think the key signature not deleting problem has existed for some time though I can't confirm this. In some cases I have added a local key signature and had key signatures appear in all instruments until I undo the key change, deleting it did not help when this happened, but it did not happen every time and I'm not sure what causes it to happen. It may have only been on measures where I had an instrument change because I know it worked properly sometimes.
At this point I have not tested many instrument changes, so I'm not sure which conditions are required to make this happen. My first test was to change from a horn in F (with atonal local key signature) to a horn in G and it worked fine, but both are transposing instruments with the same clef and I didn't check the effect of the key signature on other instruments. I'll do more testing and update this when I know more.