If no Paypal payments are registering in your Simplero account but showing as completed in Paypal, there is likely a missing setting in you'll need to adjust in Paypal.
If that occurs, try these steps provided to us by Paypal in order to resolve. This will not impact old Paypal payments but any payments going forward would start showing properly in Simplero after following the steps below:
4. Now select "Turn Off IPN"
5. Confirm Turn Off IPN
You should now see this screen:
And things should work as expected.