I recently switched gateway settings in PMPro from Paypal Express to Paypal Standard (no settings were changed with the Paypal account itself).
Ever since the switch, new subscriptions are immediately cancelled after being created. The sequence in the PayPal recent activity log is: Created, Completed, Cancelled. Existing subscriptions seem to be working fine.
Any ideas what might be causing this problem? This situation is unfortunately creating quite a headache for my client.