Hi @todor – once a masspayment is created via the API, we run the masspayment job which parses through each item and creates a transfer resource for each successful item. We recommend waiting for the "mass_payment_completed" or "customer_mass_payment_completed" webhook before making the GET call to "#{mass_payment_url}/items"
If you notice the status of the first item, it says pending which denotes that the related transfer hasn’t yet been created.
The second item which has a transfer associated with it, has a status of success.
Hope that helps! Here’s also a guide where we provide some best practices when creating a masspayment. Let us know if you have any questions!