Can't unembed font taking up 99% of filesize

I have a PDF exported from some engineering software. When I bring it into Acrobat and run PDF Optimizer, Audit space usage reports that fonts take up 99.71% of my filesize. However, there are no "Embedded fonts" listed! See http://i.imgur.com/F0m3D7G.png

I think the issue has to do with the form fields, but even after deleting all of the forms in the PDF (and all of the other content, in fact), the filesize is still 2 MB for a 2-page blank doc.

Any ideas?

I'm using Acrobat 11.0.3. A similar issue was reported here: http://forums.adobe.com/message/1974685, but you would think such a bug would have been fixed in the last four years!