epub to azw3 bug (no picture in cover SVG)
Calibre 2.76 64bit (Win7 64bit)
Small bug in 2.76 during epub-azw3 conversion (2.75 was OK)
First xtml (cover.xhtml) file in epub contains cover picture in a SVG structure. (used Sigil's "Add Cover" option, almost similar as Calibre editor same function)
Semantic of that file is empty or something other then "Cover".
(usually using "Title Page" as it is a small trick for Kindle to show cover image as a first page of a book during first book opening. Example is like that.)
Conversion to AZW3 renames a "Desert.jpg" to a "00002.jpeg" in "Images" but does not do that in a "Text" part leaving "Desert.jpg" so there is no picture shown.
In enclosed example I doubled first xhtml to another file (titlepage.xhtml) and Calibre also failed to rename picture in SVG. Output AZW3 also included