Recurring billing not creating multiple invoices on monthly basis

Summary:

We are using Order management for Service items. All items are bill only items.
While creating Recurring billing sales order we have observed that monthly invoices are not getting created.

Example

Billing frequency: Monthly 
Number of billing period: 5
Contract start Date : 1 Jan-26
Contract End Date : 1 June-26

Invoice created: 1st Jan to 31st Jan 2026 ( Single month)

Once we submit SO and Run auto invoice program. This only give one Invoice. Ideally it should give 5 different invoice for all 5 month service was given.
Order is created on 15th Sept 2026. All the dates are passed and periods are open. System should create invoice in this case for past months.