When a return is updated, and the individual reports are rerun, they will update correctly. If you then update the return again and run a combined report, the updates flow through to the new combined report; the updates do not flow through to the individual reports.
Our development team is working on getting this resolved so that they update automatically. Thank you for your patience. As a workaround, please use the following steps:
Generate the reports with the Combined reports box unticked.
Close the reports.
Re-generate reports with the combined reports box ticked.