How Do I Unlock An Invoice?
The easiest way to unlock an invoice is by clicking the "Locked" tag in the top right corner when a Service Order is loaded in the Scheduler page:
TTP will automatically "Lock" invoices after a client has made a payment or you have emailed the invoice (to help prevent mistakes). You can easily "Unlock" invoices or turn the "Locking" feature off entirely. Here is the help article explaining Locked Invoices.