PDF is so
iffy (in both directions)
https://www.mobileread.com/forums/sho...d.php?t=118605
If you really need a PDF, you might convert to something else (Word,RTF?) and use the Print to PDF option of that program.
BTW you are trying to insert a
naked <img
<img must be in a container <p <div <h#
Validate our EPUB inside the Calibre Book Editor
GIGO