Mapped Instrument "Relative Position" setting does not affect staff position of the associated input sample/MIDI note#, nor instrument group

I am trying to create notation for percussion.

I have used the Environment window to create a Mapped Instrument for two tracks, each using samples of 30+ types of percussion instrument. Double-clicking to get the Mapped Instrument Window, I then see a vertical keyboard along its left edge. When pressed, the keys correctly trigger the associated samples.

1. As instructed, I have assigned each relevant small percussion sample to a "Group" (far right column of the Mapped Instrument Window) and to a relative position ("Rel. Pos.") on the staff.
2. I then created the Mapped Instrument's "Staff Style" via [Score Window] --> [Layout] menu --> [Show Staff Styles] --> [New] --> [Mapped Style], and assigned the associated MIDI region to that style, so that the notation for that region should use the new mapped staff style I created. And sure enough, in the Staff Style window, the new instrument groups I created (in the Mapped Instrument window, step 1) ... are available in the "Assign" column of the Staff Style window.
3. The next step is to change either the "Rel.Pos." setting in the Mapped Instrument window, or the "Position" menu in the Staff Style window, to control where on the mapped staff any given instrument will appear. (Or both; the former controls individual samples and the latter controls groups of samples.) But neither setting makes a lick of difference to how a note appears on the score. For Mapped Instruments that have user-assigned instrument groups, even the "Position" menu for those voices (in the Staff Style window) makes no difference. (The "Position" menu *will* affect the positions of notes in pre-set drum groups, for pre-set samples.)

In other words, the "Mapped Instrument" window produces no impact, that I can see. (Aside from transferring instrument group names into the Staff Style window's "assign" column menus—generally, as options, but not as actual categories.)