The boxes indicate a problem rendering a font - specifically, that the font being used does not have representations for the characters it’s attempting to display. What font are those components in the report set to use?
It’s a limitation of the way we generate reports - the backing library does not support font embedding inside generated PDFs, so it relies on the fonts already in the system. There’s no real workaround, other than installing all required fonts at all locations these report PDFs might be viewed.