Hello everyone, am facing issue, while creating an invoice for a charge rule with a fixed date for a project with a sales order; for one charge rule, an invoice is generated; for another, an invoice is not generated because the sales order status is in - billed?

Did the first charge rule effectively billed the entire SO?

No

Is it using the Item sublist? Is the invoice quantity equal to or greater than the SO quantity?

yes it using item sublist and invoice and SO quantity are same.

The billing status is dependent on the SO quantity. If the invoice quantity per line equals or exceeds the related SO quantity per line FOR ALL LINES, then the SO will be considered FULLY BILLED. I think that's probably the reason why you can't bill the 2nd charge if it's going to use the same item from the SO that is already fully billed.