There is no billing order for the account, further checks show that an account is in the credit hold status.
This is expected behaviour, accounts in credit hold are not billed. With the next daily billing after account release from credit hold, it will be billed for whole period it has been in the credit hold status. If due to whatever reason you need the customer's invoice now, it is possible to release an account and click "Bill This Account".
Accounts in the credit hold are billed if PBA version is > 5.5.4 and pay-as-you-go model is enabled.