Are cross-staff beams and 'remove-empty *really* not compatible?

[Valentin Villenave]

Greetings,

NR1.2.4 says:

Known issues and warnings
Automatically kneed cross-staff beams cannot be used together with
hidden staves.

Why?

The following piece of code works well (and if you uncomment the last
line, an ugly #76 collision happens)

\layout {
  \context {
    \Staff
    \remove Axis_group_engraver
    \consists Hara_kiri_engraver
    %\override Beam #'auto-knee-gap = #'()
    \override VerticalAxisGroup #'remove-empty = ##t
  }
}

\new PianoStaff <<
  \new Staff = "up" s1*24
  \new Staff = "dwn" {
    ais16 ais'16
    \change Staff = "up"
    ais'8
    r4 r2
    \repeat unfold 23 d'1
    }
>>

-- 
Cheers,
Valentin