In the past, this has been pretty straightforward. I typically create the drawing in LibreOffice Draw because I happen to find the tools a bit more intuitive for my very limited purposes. I can then export to SVG or virtually any other format I like (I tend to like SVG for portability reasons).
I then load the drawing into Inkscape for cleanup. Once I'm satisfied, I then save it natively.
This has generally worked well with Google Docs because I can then use Inkscape to save the drawing as a .WMF file. Google Docs can import the Windows Metafile format directly.
Unfortunately, my current drawing project is misbehaving.
I'm doing a logo for a project. I did as I outlined above: created it in LibreOffice Draw; exported to SVG; opened in Inkscape, cleaned up a little; saved to SVG; saved to WMF. All fine and dandy.
Unfortunately, upon importing to Google Docs, the resultant drawing is empty. When I look back at the .WMF file by opening it in Inkscape, it's also empty.
I can even export to .WMF from LibreOffice, which I've tried. It also produces an empty .WMF.
I didn't think I was doing anything too complex. It's basically some text extruded via LibreOffice's Fontworks tools, and then shaded to my liking. I've attached a copy of the problematic SVG.
Oh, and why am I doing something so weird? Pretty simple: Google Docs integrates tightly with Google Sites, which is where I host my Web site. It's triviality itself to embed a Google Docs vector drawing into a Web page. Ultimately, I'd like this logo appearing at the top of the page.
Yes, it's a somewhat roundabout way to get a drawing into a Web page. However, it frees me from having to keep a high-res vector drawing around, separate from everything else, which is then used to generate a bitmap for use in the Web page. Google Sites can use the Google Docs vector drawing directly.
I've never had Inkscape fail to produce a great .WMF, so I'm a bit puzzled. If anyone has any suggestions, I'm very much all ears.

Thanks in advance!