View event payments does not show initial payment.

The scenario is this:

1. A front-end user in Joomla registers for an event for which part payment/pay later is possible.
2. The user pays a deposit,
3. The administrator records the payment using the back end.
4. The participant record shows the payment recorded (see attached file).
5. View Payments shows 'No payments found for this participant record'.
6. Later payments do show in View Payments.

I've done some troubleshooting, and I think it is because the first payment lacks SQL statements putting data into civicrm_entity_financial_trxn relating to civicrm_financial_item, e.g.
INSERT INTO civicrm_entity_financial_trxn (entity_table , entity_id , financial_trxn_id , amount ) VALUES ('civicrm_financial_item' , 380 , 579, 30 ) , that later payments have. The total payment amount seems to be split between the participants registered by the one person.

This could be related to CRM-18260 and CRM-19803

I plan to investigate further, but this might be a deliberate policy.