I’ve changed noteheads in normal voices, but it doesn’t seem to stick when I’m trying to change the notehead on a slash voice.
I’m afraid I don’t think you can override the notehead type of individual notes in a slash voice. You’ll need to employ a pretty ugly workaround, which is to use a normal voice for the muted note, and hide the rests you don’t want to appear in the remainder of the bar. Or you could use a regular voice for the whole passage, and override all the noteheads to be either slashes or muted as appropriate.
Gotcha, thanks! Seems like the second option is better, haha. Used to doing this in finale anyway 
I’ve just run into the exact same issue. A compounding problem is that I’m using the underlying notation of the rhythm slashes for playback, so converting one of the slashes into normal notation to display an x would display the playback notes (which won’t look pretty – the pitches used to “strum” the guitar are several octaves above the notes used to determine the chord). I could think of possibly hiding all playback notes except one, changing that to an x, and adjusting the stem length in Engrave mode. However, I’d want the x to appear on the same line as the slashes, and I’m not sure how I’d do that when playback depends on the note positions.
Are there any other workarounds (ugly or not) that you could suggest?
