Hi @Avishka ,
"Open AR Invoices" and "Pending Invoice Amount" are two completely different things.
Explanation as below
The Core Misunderstanding: Unpaid vs. Unbilled
We are comparing Open AR Invoices (invoices that have been generated, sent to the customer, but are unpaid) to the Pending Invoice Amount.
In Acumatica, Pending Invoice Amount strictly means "Unbilled." It is the amount of money sitting in the queue waiting to be put onto the next invoice when you click "Run Billing". Once an invoice is actually generated and released (becoming an AR Invoice), the amount is subtracted from the Pending Invoice Amount and becomes an actual billed amount. Therefore, the total of their Open AR Invoices should not match the Pending Invoice Amount.
The Solution
Since the project is marked Completed and there is no further billing to be done, we can simply click into the grid, change all the amounts in the Pending Invoice Amount column to 0.00, and click Save. Because the billing basis is "Amount," this field is designed to be manually overridden to reflect reality.
Hope above works!!