When I try to transpose a staff that has no keysignature only some notes are transposed, the staff does not receive a keysignature (as it should). Is this a bug or am I missing something? I solved it myself by putting the right keysignature in front and re-doing the transpose with 0 semitones.
Jos, since the key signature itself is an "object" Noteworthy can't change it unless it exists. You can insert a key signature of C maj (which will be displayed as an F natural) before transposing the staff in order to give Noteworthy something to change.