Bug? Breaking pedals

[Antti Kaihola]

For some reason there a gap in the pedal bracket for bars 12-21 in the
score below although it should be continuous from the beginning to end.
If I replace the music with a single repeating note, the pedal is ok
too. Strange.

\score {
    <<
        \relative des, {
            \clef bass
            \override Staff.DynamicText #'extra-offset = #'(-5 . 0)
            <des as'>1\f | <des as'>  | <des as'> | <des as'>~ |
            <des as'>~   | <des as'>~ | <des as'>\fermata |
            \clef treble
            <c'' g'>2-> <c g'>-> | <c g'>-> <c g'>-> |
            <c g'>-> <d a'>4 <es b'>4 | <e b'>1->~ |
            <e   b'>             | 
            \time 9/8 s1 s8      |
            \time 4/4 s1         |
            s1*7 |
            \clef bass b,8-.-3 b-.    b-. b-. b-. b-. b-. a-. |
            \clef bass \dynamicUp
            <des, as'>1->\f | <des as'>->  | <des as'>-> |
            <des as'>4-> <c g'>2.->~ |
            <c    g '>4 \stemUp
            ges''8-2_\markup { \italic vapaasti } [( as b]) 
            \stemDown
            a-2[(  g   f]) \stemUp | 
            ges[( as]) \stemDown
            a[(    g   ]) \stemUp
            ges[( as]) \stemDown
            a[( g]) \stemUp | 
            ges[( as])  g-1[(  as?-3] \stemUp
            g  [  as   g   as]) | s1 | }
        
        \\
        
        { 
            \set Staff.pedalSustainStyle = #'mixed
            s1*3\sustainDown | 
            s1*4\sustainUp\sustainDown |
            s1*3\sustainUp\sustainDown | 
            s1*2\sustainUp\sustainDown | s8*9 | s1 |                
            s1*8\sustainUp\sustainDown | 
            s1*3\sustainUp\sustainDown | 
            s4 s2.\sustainUp\sustainDown |
            s1*4 | 
        }
    >>
}