Thank you. Glad to hear your issue is resolved.
I have fixed my issue too.
An old plugin had created a PayPal Notification URL which needed overwriting manually.
The standard PMPro advice is not set the IPN URL (https://www.paidmembershipspro.com/setting-setting-ipn-urls-paypal/), but in this instance setting it was necessary.
Also, in PayPal Instant Payment Notification (IPN) settings, it was necessary to check ‘Receive IPN messages (Enabled)’, rather than ‘Do not receive IPN messages (Disabled)’ as advised in https://www.paidmembershipspro.com/setting-setting-ipn-urls-paypal/.
This fixed it.
All seems to be working ok now.