Rehearsal mark positioning above groups

[Stu_M]

That option is only meant to apply to rehearsal marks that would potentially collide with the systemic barline (e.g. above the strings), and not to rehearsal marks above the system. Apparently the fact that it does apply to single staves is the bug.

Horizontal offset for rehearsal mark aligned with systemic barline not working with multiple staves

It’s probably not sufficiently clear from the way the option is described, but the idea behind this option is that if you end up showing rehearsal marks on a staff in the middle of a system, the offset should be applied to avoid a collision with the systemic barline; it’s actually not supposed to take effect when the rehearsal mark is above the top staff or below the bottom staff of the system, so in fact the bug here is that it applies when there is only a single staff.