I created a custom notehead set, when I choose to hide notehead in Engrave Mode, it still is visible. With the Dorico standard notehead sets the notes are hidden when you hide them in Engrave mode.
If that’s a SVG graphic, then yes, I’m afraid that is a limitation. Either use a regular notehead rather than your special one and hide that, or consider making your special notehead as a font character using a font editor.
Yes of course, that makes sense. I hadn’t thought of choosing the invisible notes in any other notehead set. I’ll also look into making a Font for different symbols, thank you!