Good evening, Scott,
This problem was caused by a policy change at PayPal.
For over a year and a half your plugin worked well until it did not.
Our Rotary Club PayPal account was registered as personal. PayPal recently decided that donations cannot be made to a personal account but only business accounts. We are in the process of changing to a business account.
Thanks for your reply and support.
Encryption is off and has never been on.