When upgrade wkhtmltopdf to 0.12.6, it came to such messages and the image did not show in the target pdf:
Warning: Blocked acc
Just bumping this thread with a correction in case you're still getting the same error in spite of using:
--enable-local-file-access
For some reason, this cmd line argument does not work when being specified after input/output files, you have to write this argument right after wkhtmltopdf.exe.
So
wkhtmltopdf.exe --enable-local-file-access input.html output.pdf
instead of other variants.