Ever come across a passage of music that looks like this?
These are rare gems, but you may encounter them occasionally upon importing a transposed instrument in a score via MusicXML or in other instances.
This music is transposed up a triple-diminished third from where it should ordinarily be displayed. Ever learn about a triple-diminished third in theory class? Me neither — that’s because it’s enharmonically equivalent to a unison.
Fortunately, you can quickly fix this and other similar passages by selecting the passage and hitting Return to enharmonically change the notes until they look correct:
Note Input > Note Input > Transpose (Shift-T) will also do the trick, if you set Transpose by interval to a perfect unison (up or down).