Fillable Saveable Form - Fields appear to be blank but aren't

We have a fillable savable form created with Adobe Acrobat 8 Professional. Sometimes the form emailed back to our office and opened in Reader Version 9 and it the form appears initially to be blank unless you click into the field - you can then see the data. However, you can't print the form with the data displayed. If using Reader version 8, then if you click the highlight button it acts like a toggle switch to view the data in the fields; however you still can't print.

Any ideas on what is causing this and how we can fix it?