Marketpress 2.4.1 No longer talks to Paypal

After upgrading the plugin to 2.4.1 instead of being redirected to the PayPal payment page I received the following error message: "10400 - Transaction refused because of an invalid argument. See additional error messages for details. - Order total is missing."
I went ahead and rolled back to the former plugin version and works fine however I really like staying updated. Can you please look into this?