Unexplained docs that should read -

Unexplained documents that should read

If you have a document that really ought to read in FC, and probably does read properly in the FlexiLayout studio it might just be a corrupt PDF. Try opening the file then File… Print… to XPS. This forces the file to re-render. That technique has worked several times now, each after spending many minutes tearing hair out trying to blame the FlexiLayout.