Request help with cueDuring

[Patrick Karl]

The snippet below is extracted from the 1st 6 measures of Pachelbel's Kanon.  I 
am trying to insert cue notes into the parts for the soprano and the alto.  The 
soprano cue notes are taken from the bass line, while the alto cue notes are 
taken from the soprano line.  However, the alto cue notes are not what I 
expected, namely, a full measure rest rather than the soprano notes from 
measure 2.

I have read about this in the Notation Manual and looked at the snippets in the 
Snippet Repository, but have not succeeded in figuring it out.  Could someone 
please give me a clue?  (Note that even in the Soprano part the full measure 
rest looks like it is a cued rest rather than a standard full measure rest on 
the 4th line of the staff.  I don't understand that either, but I can live with 
it.)

\version "2.14.0"

B = \new Voice \relative c' {
    \set Staff.instrumentName = #"Bass "
        \clef bass

        d4 a b fis              % 1
        g d g a         % 2
        d4 a b fis              % 3
        \bar "|."
}

S = \new Voice \relative c''' {
        \set Staff.instrumentName = #"Sopr "
        \clef bass
        
        \addQuote "B" { \B }
        \new CueVoice \with { instrumentCueName = "Bass" }
        \cueDuring #"B" #DOWN { R1 }    % 1
        \clef "treble^8"
        fis4 e d cis                                    % 2
        d a b fis                                               % 3

        \bar "|."
}
 
A = \new Voice \relative c'' {
        \set Staff.instrumentName = #"Alto "
        \clef treble

        \addQuote "S" { \S }
        R1                                                                      
        % 1
        \new CueVoice \with { instrumentCueName = "Soprano" }
        \cueDuring #"S" #DOWN { R1 }                            % 2
        b4 a b cis                                                              
        % 3
        \bar "|."
}

global= { \time 4/4 \key d \major  }

\score {
        \new ChoirStaff << 
                \new Staff { \global \S }
                \new Staff { \global \A }
                \new Staff { \global \B }
        >>
        \layout { }
}