During the bulk invoice creation process, you can toggle the option to omit $0 invoices from being created
What is considered a $0 invoice?
Any invoice in which no services are to be billed in that period.
Example: On request customer who does not have any active services at the time of billing.
Customer has an open balance but no services, is that a $0 invoice?
Yes. The $0 is based on the total of current services, not on the open balance. If you want to create an invoice only for their past due balance, we recommend not enabling this feature or creating an invoice within their profile
What happens to the invoices I did not generate?
They're still available. You can choose to create those invoices in bulk or individually.