http://bugs.winehq.org/show_bug.cgi?id=29347
--- Comment #7 from Anastasius Focht focht@gmx.net --- Hello Rosanne,
--- quote --- Files saved in Excel under XP display the previews fine in both Wine and Windows. --- quote ---
Good. That means that preview works in general.
--- quote --- Files saved in Excel under Wine just display the blank rectangle in both Wine and Windows. Tested in wine-1.7.19-56-gee13e10. --- quote ---
Well, my tests were more successful. I had a chart image displayed on white background when generating the preview with Wine. I don't know maybe it's workbook/content specific (test other examples?).
OP reported "preview is unavailable." which is clearly not the case since I have a preview image displayed if properly created. If your preview doesn't completely work for whatever reasons it's likely a different problem. You could start with providing various workbook examples as test-cases to make this bug still useful (change the summary accordingly).
Regards