Kindle Previewer doesn't seem able to generate .azk files for iPad/iPhone if one of your books HTML files has inline <svg> graphics -- instead of generating the .azk, it fails with a dialog reading "Kindle Previewer has failed to convert the book."
I first ran into the issue using a rather complicated SVG exported from InkScape, but it also happens with the SVG sample code in the Publishing Guidelines PDF (pages 24-25), or even just an empty <svg></svg> tag; comment out or delete the SVG tag, and the book exports just fine.
I'm using Previewer version 2.92 on OS X 10.8.5, and my book is fixed-layout, if that makes any difference.
Anybody else run into this and know a work-around, or even know if inline SVG works on Kindle for iOS at all? FWIW, linking to a separate SVG file via an <img> tag or even a CSS background rule compiles and looks great on my iPad.