tie-grace bug (?) ver 2.9.16

[Mehmet Okonsar]

this code compiles (ver. 2.9.16)well only if the grace notes are omitted at 
the left hand part, otherwise the ties at the right hand do not get drawn..
is this a bug?
===================== CODE====================

\version "2.9.16"
\include "english.ly"
%---------------------------------------------------------------------

%---------------------------------------------------------------------
forceAlterations =
   #(define-music-function (parser location music)
        (ly:music?)(music-map (lambda (m)
            (if (eqv?(ly:music-property m 'name) 'NoteEvent)
                (set! (ly:music-property m 'force-accidental) #t))
                m)music)music)
%************************************************************************** 
PIANO
%===================================================================== PAPER 
BLOCK
\paper
    {
        #(set-paper-size "a4" ) % ----- set other formats here

    }
%============================================================================== 
Piano RH

\score {
\forceAlterations {
\new PianoStaff {
<<
    \context Staff = "RH"
    { \clef treble

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% B A R :19
\time 11/8
#(set-octavation 1 )
<ds'''' fs'''' as''''>4\f->
#(set-octavation 0 )
<cs' gs'>8~ 
%this tie does not print if there are graces 
%at the left hand, remove the graces and it does print
<cs' gs'>2.~ <cs' gs'>8[ 
#(set-octavation 1 )
<c'''' d'''' f'''' g'''' a'''' b''''>8]->\ff->
#(set-octavation 0 )

\bar "|."
    
    }

    \context Staff = "LH"
    { \clef bass

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% B A R :19

r4
r8
\stemDown
\grace {e32[\f\<( g' d' a,] }
\stemNeutral
<e,, a,,>1\ff->)

\bar "|."
    
    }
>>
}
}

\layout { indent = 2\cm
    \context
    {
        \Staff
            \remove "Time_signature_engraver"
    }
  }

}







===================== END=====================
-- 
Mehmet Okonsar,
pianist-composer-conductor
www.okonsar.com