Fatal error when registering event participant in back-office for event with date-driven discounts

When registring an event participant for a paid event with early registration discounts we get the following fatal SQL error:

Cannot add or update a child row: a foreign key constraint fails (`d7_civi43_crm`.`civicrm_financial_trxn`, CONSTRAINT `FK_civicrm_financial_trxn_from_financial_account_id` FOREIGN KEY (`from_financial_account_id`) REFERENCES `civicrm_financial_account` (`id) [DB Error: unknown error]

To reproduce:

• Create new event
• Paid event - yes
• Configure a few default price options (quick config)
• Enable discounts by date - include today's date in the date range
• Add some discounted price options - I set mine to have the same labels as the non-discounted options but lower prices
• Click "register participant" in event links at the top
• Record payment by cash (but not a partial payment)