One possible explanation for the absence of a generated invoice is a recent adjustment to the billing cycle. If changes have been made to the billing cycle start day either at the account level or within the global settings, the system will generate invoices according to the newly selected day. It's important to note that any changes made prior to the new billing cycle will prompt the system to close the previous cycle and generate an invoice based on the new start day.

For example, suppose the billing cycle initially began on the 1st of the month and was changed to the 8th of the month on the 5th of January. Since a full invoice was already generated on January 1st, the system won't generate a new invoice on January 8th, the start of the new billing cycle. Instead, it will wait for the next billing cycle, starting on February 8th. This February 8th invoice will include info from February 1st to February 7th, and also from February 8th to March 7th (if the subscription is invoiced upfront), accommodating for the billing cycle change. Later on, in the following month, the billing cycle returns to normal, invoicing from March 8th to April 7th since the system has already adjusted for the billing cycle alteration.

Another scenario that may lead to an unissued invoice is the cancellation of a previously generated invoice. By accessing the account and navigating to the invoices tab, you can preview upcoming invoices by clicking the "see preview" button. Deleting line items from any of these upcoming invoices will prevent the invoice from being generated.

In cases where the subscription has been extended beyond the last billing day, the system will generate an invoice until the next billing cycle, this invoice will contain the prorated unbilled part after the subscription was supposed to end plus the new month if your settings are to bill plans upfront.