Alt+m not working for unhitched percussion

I have exported a midi drum track from cubase and trying to notate it on two different staves on Dorico. Problem is, I cannot use alt+m for moving the notes down a stave. What could be the problem?

If I recall correctly, this is due to a drum staff actually containing multiple instruments (it is a Percussion Kit) and your two drum staves contain a certain combination of instruments at different staff positions.

I think the easiest thing to do is to view your drum kits as single-line instruments i.e. the snare will be on its own staff, the high-hat will be on its own staff… and then copy, for example, the old snare music to your new snare staff.

Then, reapply your 5-line presentation type.

Does any of this make sense?