Issue with last update (2.2.1)

Hello, Thanks for the plugin;
After I updated GetPaid to 2.2.1, and tested (with test Gateway) a payment, although I get the page thank you for your payment and the invoice is noted as paid on the backend, the email of confirmation is not sent and the function _wpi_wpinv_status_paid( $invoice_id, $old_status ) that I added is not working anymore.
If I roll back to the previous version of the plugin (2.2.0) that works again.
Thanks!