Bravura svg font

[Paul Booker]

Hi,
I'm a new use of lilypond-windows on Win 8.1 64bit and Win 7. First of all,
thanks for wonderful software; I'm generating many snippets for educational
purposes.
My main problem so far is getting the bravura alternative font to appear. I
don't mind trying a few things, but this problem has me stumped.
Bravura works fine when I produce png images, but I get something else when
I try to make an svg.
The svg is fine with Lilypond font, and I am only trying to change the clef
to bravura bass clef.
I put this in cmd.
"c:\Program Files (x86)\LilyPond\usr\bin\lilypond-windows.exe" -dgui
-dbackend=svg -dpreview file.ly

I have this in the file.ly
\version "2.18.2" 
\include "custom-music-fonts/smufl/definitions.ily"

and
\override Staff.Clef.stencil = #smufl-clef

The offending part of the svg, instead of the clef path, is

<text transform="translate(0.8000, 1.5000)" font-family="Bravura"
font-size="3.9200" text-anchor="start" fill="currentColor">
<tspan>
</tspan>
</text>
Evidently, it is trying to be bravura but from the text font perhaps?
I got the same result when I tried 2.19.35.
Would I have better luck with Linux? (last resort). Thank you