after signing, images replaced wit black boxes

Hi,

The issue is Adobe Fill & Sign app on iOS, replace some Arabic text/Images (considered images, in original pdf file) to black boxes; after signing the file and sharing it back

The other text/images having non-white background are kept as is

The PDF file generated, through MS-Word and MS-Excel then merging together (2 pages) in one PDF file, using ilovepdf

We have classification tools in the organization, but excluded for the case (I don’t think, it’s the issue); and just mentioning to give full view on the case

The generated PFD file, shows PDF producer as iLovePDF

After signing, the producer is iOS Version 17.4.1 (Build 21E236) Quartz PDFContext

How to avoid those black boxes, from replacing the text/images?

Please help