I am getting the same error.
Calibre's version is 4.3 64-bit [08 Nov, 2019]
KFX Output plugin's version is 1.33.0
Kindle Previewer's version is 3.35.0
OS version is Windows 10 64-bit 1903
The book to be converted is
Frankenstein by Mary Shelley.
The error is:
Code:
ERROR: KFX conversion failed: <p><b>Cannot convert Frankenstein</b><br><br><b>KFX creation error:</b> Invalid local symbol created: rsrc7</p>
Many thanks in advance,
Jaak