Hi,
I configured an automation schedule for the Run Project Billing process. However, several of the projects that were completed still generated an invoice even though the items were billed already. I did know for several line items this happened on after Run Billing was done the completed % column like below increased from 100% to 200% causing an invoice to happen. The billing rule is set to Time & Material .

Here is the billing rule for Time & Material:

This billing rule also includes a progress billing:

Could the billing rules be causing an issue. Some parts of the revenue are T&E and others progress. Let me know or if you need more detail.
Thanks,
Frances