Epub->AZW3 --- embedded font display is wonky

[GrannyGrump]

I created a (public domain) epub in Sigil, about 2.5 mb., converting to AZW3 with calibre version 2.28. I have embedded a font for large drop caps and divider/decorations.

When I view the resulting azw3 file in the Kindle Previewer, the drop-caps look fine. But the decoration glyphs are all displaying very very small.

In contrast, when I use Kindlegen to convert, all the glyphs are correctly displayed.

When converting, I have settings as follows:
Look and Feel: everything is Unchecked.
Heuristic is disabled.
Page Setup is set to Default Input, Kindle Fire output. (Kindle Voyage gives same result)
Table of Contents: none
Search and Replace: none
AZW3 Output: Do not add TOC is checked, all others Not Checked.

I click the button to Show Job Details, but no report is displayed.

I tried mapping one of the glyphs to a regular "Latin" character (asterisk), but that made no difference. I tried several different settings in the epub CSS and html (different font sizes, margin-settings, using paragraphs instead of divs, and more).
Nothing that I have tried makes any difference. I am at a loss how to fix this.

Is this possibly a calibre bug?

Help, anybody?

[kovidgoyal]

Disable font size rescaling in the look and feel section of the conversion dialog

[GrannyGrump]

That's the solution! Thank you so very much!

I prefer to use calibre for the conversion -- more control, and a slightly smaller file-size.
(Now I just have to learn how the controls actually work...)

Thank you for a superior software.