I guess that it's some bug of librsvg?
I tried the easiest example:
\version "2.19.42"
\paper {
tagline = ##f
}
\markup "Hello World"
which produces:
<svg xmlns="http://www.w3.org/2000/svg";
xmlns:xlink="http://www.w3.org/1999/xlink"; version="1.2"
width="210.00mm" height="297.00mm" viewBox="0 0 119.5016 169.0094">
<!-- Page: 1/1 -->
<text transform="translate(5.6906, 2.8453)" font-family="serif"
font-size="2.2001" text-anchor="start" fill="currentColor">
<tspan/>
</text>
<text transform="translate(5.6906, 5.5183)" font-family="serif"
font-size="2.2001" text-anchor="start" fill="currentColor">
<tspan>
Hello World</tspan>
</text>
</svg>
EyeOfGnome and Gimp - which use librsvg just like rsvg-view - do not
display anything.
The problem is:
fill="currentColor"