We just checked WA knowledge base:
"If Wild Apricot does not receive a payment confirmation (which happens for one
of two reasons: either user has not completed his payment at PayPal or in some
rare cases the confirmation message from PayPal did not reach Wild Apricot),
transaction will stay in Pending status and in 1 hour the system will
automatically send a notification to the administrator."
We never received any notification about pending payment although we did have a few pending payment history in payment log.
Can you check this for us?