Filling a pdf with write_fillable_pdf does not work for this pdf

[XaverStiensmeier]

I am unsure whether I am just making an obvious mistake, but I tried to create myself some visual clues for the form fields, but the resulting generated pdf is unchanged:

PDF https://www.sparkasse-emh.de/content/dam/myif/spk-mittelmosel-emh/work/dokumente/pdf/allgemein/sepa_lastschriftmandat.pdf

from fillpdf import fillpdfs

# Get form fields from the PDF
form_fields = fillpdfs.get_form_fields("sepa_lastschriftmandat.pdf")
print(form_fields)

# Update form fields with their field names (for testing)
for key in form_fields:
    form_fields[key] = key  # Assign field name as value

print(form_fields) # change can be seen

# Write updated fields to a new PDF
fillpdfs.write_fillable_pdf("sepa_lastschriftmandat", "ls_form_names.pdf", form_fields, flatten=False)

I am unsure how to debug this as I am not getting an error.

[stillru]

#68 - same