Filling Image field in PDF not working

Problem/Motivation

Hi, I'm trying to use the module to fill an Image field in the PDF via a Node image as indicated in the documentation ( https://www.drupal.org/docs/8/modules/fillpdf/usage#image-stamping → ).

But for the moment, I can't get the expected result.

I've used the test pdf "fillpdf_test_v3.pdf" in the test module but I can't get it.
Same thing with a custom PDF "fill-pdf-image.pdf"

Maybe I'm doing it in the wrong way.

Any clue as to why ?

Thanks