bubble plot: .gnumeric -> .xls -> .gnumeric round trip fails

[John Denker <jsd av8n com>]

Files can be found in this directory:
  http://www.av8n.com/physics/bugs/

  ssconvert fci-bubble.gnumeric fci-bubble.xls
then
  ssconvert fci-bubble.xls fci-bubble2.gnumeric

The original file fci-bubble.gnumeric works as expected, as
desired.  There are ordinary bubble plots, where each bubble
has a specified X, Y, and diameter.

In the munged file, fci-bubble2.gnumeric, the X-coordinates
have vanished.  Check the "data" in "series1" in either
bubble plot.

Asking gnumeric to read the .xls file directly produces the 
identical wrong result.

Note:  At the moment, I have no idea whether there is an
export problem, an import problem, or both.  I am trying 
to obtain more information about this.

Workaround?  None that I know of.

Priority:  This has a much higher priority than the bugs
I reported earlier today.  Some of my colleagues are wedded
to MSXL, and they expect me to send them a working .xls file.