This issue has already been fixed in Scour (Scour is the SVG optimizer that is used in Inkscape when you save as "Optimized SVG") and the fix [1] is included in Scour 0.35.

There are also some major improvements concerning the "Optimized SVG" export via Scour in Inkscape 0.92, most notably:
If you want to give it a try I suggest you install a 0.92 pre-release!

Regards,
Eduard

P.S. As I'm the one who implemented the fixes in Inkscape and became a maintainer of the Scour module recently feel free to let me know if you have any issues or suggestions. Requests regarding the Scour module itself (i.e. not specific to the implementation in Inkscape) are best submitted directly to the projects issue tracker on GitHub [3].

[1] https://github.com/scour-project/scour/commit/584407625853e75efb679572a0199028be5f31d1
[2] https://github.com/scour-project/scour/blob/master/HISTORY.md
[3] https://github.com/scour-project/scour


Am 25.10.2016 um 22:20 schrieb Amelia Bellamy-Royds:
The problem is not with "Convert CSS attributes to XML attributes" specifically, but with the "Create groups for similar attributes".  The exporter script is inserting a <g> inside a <text>, which is invalid and should not render in a conforming SVG implementation.  It's an error that Inkscape renders the nested <tspan>, although not one that would usually be a problem!  The exporter script either needs to use another <tspan> for the grouping or just skip grouping within a <text> element altogether.

~ABR

On 25 October 2016 at 13:40, Stefan Tauner <tauner@...3436...> wrote:
Hi,

I have tried to submit a bug report via launchpad multiple times during
the day but it seems to not like me today, thus I am submitting it via
the ML.

When I save an optimized .svg with the option "Convert CSS attributes
to XML attributes" enabled with Inkscape 0.91 (Ubuntu 16.04), any
application that I have tested but Inkscape do not display some parts
of an image with the resulting file. I managed to create a MWE that
should be handy enough for a successful analysis.

Attached you can find the original Inkscape .svg and two
optimized .svg files created with the CSS option turned on and off
respectively. When the option is off then all applications render the
dot fine, when it is on only Inkscape recognizes it.

KR
--
Dipl.-Ing. Stefan Tauner
Research and Development
Embedded Systems Department

University of Applied Sciences Technikum Wien
Hoechstaedtplatz 6, 1200 Vienna, Austria
T: +43 1 333 40 77-316
E: stefan.tauner@...3438...at
I: embsys.technikum-wien.at
I: www.technikum-wien.at

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