Why do I get large black rectangles on ODG file when converting from PDF?

There seems to be one black rectangle generated per line in original PDF table. Can I adjust ODG conversion parameters to not generate these rectangles?
Conversion to ODG.odg

What’s your target? Would you like to edit the PDF’s content?

There are lots of shapes in your Draw file, that means that the original PDF file has got lots of elements which are spread all over the slides. And LO is obviously partly not able to “interpret” them in the right way.

Try out Inkscape for converting and check if there are similar or better results. (Inkscape can only convert single pages (not ranges), so it is more cumbersome. But if it worked better you could better manage the editing.)

For better understanding: Upload the “source PDF file” for checking the conversion.

Yes my goal is to modify the PDF content (edit text, add arrows to maps, add enlarged maps etc.) and reconvert it back to PDF. I was not able to upload the source file since the PDF format is not accepted as a valid file extension. Is there another way?

Additional info: Up to a few months ago everything was working fine. The black rectangles started to appear when the style of the arrow symbols in the original PDF file was changed. The file originator (RWGPS.com) is as puzzeled as I am regarding these new rectangles.

I will look at Inkscape also.