You have a fresh installation of WHMCS. You have done inbound transfers for a couple of domains and then you notice that invoices are not going out correctly.
Upon examining the Domain Registrations list you notice that for every inbound transfer the next due date is incorrect, it’s basically set the date you initiated the transfer.
The default WHMCS Automation Setting for domains has a “Domain Sync Settings ‘Sync Next Due Date’ which is not selected by default.
Tick this box to have due dates synched.