I'm using the below PHP code to attach a payment to a customer / partner

$payment_id = $odoo->get('account.payment', 'create', array(array(
    'date'                  => date('Y-m-d', $invoice['date']),
    'extract_state'         => 'no_extract_requested',
    'journal_id'            => 8,
    'partner_type'          => 'customer',
    'payment_type'          => 'inbound',
    'partner_id'            => $invoice['partner_id'],
    'amount'                => abs($invoice['amount'])
)));

This appears on the accounting -> Customers -> Payment screen absolutely fine. I manually approve / post this payment.

When looking at the partner account though, there is no payment visible on their account.

What am I missing?