Text spanner with multiple voices

[Misarenkov Timofey]

Hi.
I just trying to draw a barre, but seems its not always working. Below
i wrote test case having two text spanners. The first barre (over
single voice melody) is shown great. The second one draws only line but
no text. How to make text visible in the second case?

Thank you.

\version "2.13.17" 

#(ly:set-option 'delete-intermediate-files #t) 
\relative c'' { 
  \override TextSpanner #'bound-details #'left #'text = #"III"
  % first barre. This drawn right.
    c4\startTextSpan c c c\stopTextSpan

  % second one. There no text "III"
  << {c4\startTextSpan c c c\stopTextSpan} \\ {g, g g g} >>

} 
_____________
Best regards,
Timofey