On Monday, 11 Jan 2021 at 15:03, Loris Bennett wrote:
> I'm only exporting to PDF not HTML and I am creating the image in the
> source block as a PNG.  I am then viewing the resulting PDF file either
> using a PDF viewer (evince) or directly in Emacs.  The file
> blackboxmodel.png is created, but not inserted into the final ecm.pdf.

Okay, thanks for clarifying.  If I export ecm.org to PDF via LaTeX,
asking for a PNG image, it works just fine for me.  Strange.

Hopefully somebody else can chime in and maybe give some clue as to
where to look.  I've attached the ecm.org file again.  This exports to
both article and beamer PDF and, for that matter, to HTML.

-- 
: Eric S Fraga via Emacs 28.0.50, Org release_9.4.4-179-g5b5c42