Hi,

In Odoo accounting, you can handle by this way..

1. Create the Advance Payment:
   • Create a new journal entry to record the advance payment received from the customer.
   • Debit the bank or cash account to reflect the increase in cash.
   • Credit a liability account (e.g., Deferred Income) to represent the advance payment received.
2. Create the Invoice:
   • When you create an invoice for the customer, include the products or services being provided. 
3. Allocate the Advance Payment from the Deferred Income account:
   • Apply the advance payment received to the invoice to allocate the amount from the liability account.
   • In the invoice, add a new line and select the Deferred Income account and allocate the amount in minus.
   • Odoo will automatically create a journal entry for the invoice
     

By the way, could you please try this option and let us know how it works, particularly in terms of how the Amount Due is calculated?