\version "2.17.26"

form = \new Staff \with {
  \remove "Time_signature_engraver"
  \remove "Clef_engraver"
%  \remove "Bar_engraver"
  \remove "Staff_symbol_engraver"
  \remove "Axis_group_engraver"
} {
  \tag #'mild { s1 * 6 }	% creates a mild misalignment
  \tag #'moderate { s1 * 14 }	% creates a noticeable misalignment
} % form


melody = \new Staff \relative c'' {

  \key bes \major
  \time 4/4
  \tag #'mild { R1 * 5 }	% creates a mild misalignment
  \tag #'moderate { R1 * 13 }	% creates a noticeable misalignment
% this triggers the bug:
  \tag #'bug { e1 } % g'1 (absolute g'') also triggers
% this does not trigger the bug:
  \tag #'nobug { f1 } % many other things also fail to trigger the bug

} % melody


harmonies = \new ChordNames \chordmode {
% choice of chords does not seem to matter

  ees4. bes8:m9 s2
  bes4.:m9 ees8 s2
  ees4. bes8 s2
  bes4.:m7 c8:m7 s2

  \break
  ees4. bes8:m9 s2

} % harmonies

music = \new Score {
  <<
    \form
    \harmonies
    \melody
  >>
} % music

\markup \sans "Mild misalignment in bar 5"
\score {
    \removeWithTag #'moderate   % leaving mild
      \removeWithTag #'nobug    % leaving bug
        \music
}

\markup \sans "No misalignment"
\score {
    \removeWithTag #'moderate   % leaving mild
      \removeWithTag #'bug      % leaving nobug
        \music
}

\markup \sans "Moderate misalignment in bar 5"
\score {
    \removeWithTag #'mild       % leaving moderate
      \removeWithTag #'nobug    % leaving bug
        \music
}

\markup \sans "No misalignment"
\score {
    \removeWithTag #'mild       % leaving moderate
      \removeWithTag #'bug      % leaving nobug
        \music
}