Once an invoice is sent, there should be an option to make changes and send the updated version back to the customer. Currently, I have to create an entirely new invoice for minor corrections, like fixing an incorrect date.

Hello,
Appreciate the patience on this but happy to announce that the ability to edit sent and read invoices is now available in the Web platform. This should allow users to quickly update information on previously sent invoices to customers.
Should you have any other inquiries, please feel free to reach out to support@bookipi.com
Thanks,
Elaine