No drumset editor on some staffs?
I cannot trigger the drumset editor by clicking "n" on two of the percussion staffs in the attached tuplet exercise score. To try it, go to the fifth staff down with the instrument name "4:4" , or the seventh one down, "5:4", click on the staff and then press "n". Unlike the other staffs, no drumset editor appears.
It's an imported file from Musescore 2. Perhaps it's corrupt? No corruption message appeared when importing it.