PayPal Instant Payment Notification Warning

Question:
Getting PayPal Instant Payment Notification Warning even after having replaced all Donate buttons

Product:
Wix Editor

What are you trying to achieve:
Resolution of error condition or elimination of false errors

What have you already tried:
Replaced Donate buttons on the website (oratoriosocietynj.org) Home and Support Us pages.

Additional information:
Frequent (at least daily) emails with the following information:

"Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:

"https://premium.wix.com/lib-mbapi/include/modules/gateway/return/paypal.php

“If you do not recognize this URL, you may be using a service provider that is using IPN on your behalf. Please contact your service provider with the above information. If this problem continues, IPNs may be disabled for your account.”

Anyone using PayPal who’s familiar with this error please chime in. Thanks.

Scott Miller