"Select forms to send" is empty

When we attempt to email payslips or payment summaries, we get stuck at the "Select Forms To Send" screen, the lists are empty.
We have been previously emailing both fine until upgrading from Reckon Accounts Premier 2017 to Reckon Accounts Premier 2018. We have a single computer running the program locally, windows 10. We have tried disabling windows defender, running as administrator, and opening and closing the File > Send Forms windows over and over. None of which have worked.