Returned filled-in form displaying entries only one field at a time

Hello,
I made a form in Designer (enabled for Reader) which is sent to patients by our nurses. The patient fills in the form and generally saves it and returns it by e-mail. Recently, after successfully using the form for quite a number of months, several forms came back with an odd feature. The form seems largely blank, and prints as a blank form. If the nurse clicks in a given field the information that the patient entered appears. Only one field, nowever, displays at a time. The nurse is able to collect the info by clicking the fields one at a time and laboriously copying and pasting it into another document--but--especially given how overworked our nurses are right now--this is hardly optimal. Two of the three pdfs with the problem were sent back to us from the Caribbean--if this is at all relevant. We have gotten completed pdfs from Africa and Asia without any problems.
Any help would be VERY appreciated.
Thank you!

Gail