\after positioning in voices

[Robert Garrigos]

I have this code which uses \after to position dynamic marks in the right place 
where I want them:

\version "2.25.14"
\language "english"

example = \relative c' {
  \clef treble
  \key c \major
  \time 5/4
  {
    \after 2\< \after 8*7 \>
    \repeat unfold 10 {e16 f} \!|
  }
}

\score {
  \new Staff \example
}

which prints:


Trying it with a two voices fragment, doesn’t work:

\version "2.25.14"
\language "english"

example = \relative c'' {
  \clef treble
  \key f \major
  \time 5/4
<<
    \new Voice {
      \voiceOne
      \stemDown <a c>2 \stemNeutral <f a>4 <f a>2
    }
    \new Voice {
      \voiceTwo
      \after 2 \< \after 8*7 \!\> \after 2 \!
      s2 d8(c b2)
    }
  >>
}

\score {
  \new Staff \example
}

which prints wrong music:


commenting out the \after line, prints the right music:

\version "2.25.14"
\language "english"

example = \relative c'' {
  \clef treble
  \key f \major
  \time 5/4
<<
    \new Voice {
      \voiceOne
      \stemDown <a c>2 \stemNeutral <f a>4 <f a>2
    }
    \new Voice {
      \voiceTwo
      % \after 2 \< \after 8*7 \!\> \after 2 \!
      s2 d8(c b2)
    }
  >>
}

\score {
  \new Staff \example
}


How can I have the dynamics in the same place as the first example in the two 
voices fragment?

Thanks.

Robert