Although I knew it was probably a long shot, I had the site upgraded to version to 2.7.7. I was hoping that some problem would be sorted out through an upgrade. No such luck. Does anyone have an idea? Receiving an emailed electronic copy of the student's certificate is a critical feature for my site - I can't imagine others aren't using it.
My hosting vendor, Moonami, is having the same issue on sites they generate from scratch using 2.6.x or better. This eliminates the variable that I configured something wrong. It worked prior to a migration / upgrade on version 2.5.2.
Any help, theories, or even someone else admitting they have the same problem would be very helpful.