Thank you for your post, and I apologize for the late reply.
How are you saving PDFs of your records? Are you selecting "Records being browsed" or "Current record"?
Pull down the View menu and select Preview Mode. This is what is being sent to the print driver. If the "white boxes" are displayed in Preview Mode, then those characters will appear in the PDF file.
Are you using the PDF button in the Print dialog box? Or, are you using "Send Records as PDF" from the File menu?
Any additional information you can provide may be helpful in determining possible causes.