I am working with a fresh Indico 3.0 installation. To test the paypal payment method, I created a conference with a fee of 0.1 Euro. After registration of a test participant, I proceed to checkout and pay with paypal, but the registration status stays at “not paid” although I have received a payment confirmation mail from paypal. If I try to pay again, the paypal site tells me that this invoice is already paid. So, paypal knows that it is paid, but the indico status is still “awaiting payment”.
I have configured the paypal plugin with the email address of our business paypal account. In the conference settings, I first had the bank transfer option enabled, later, I also enabled the paypal option and disabled the bank transfer option.