After a change request is complete, the information in the Change Log is no longer available from the workflow form. To save a copy of the Change Details report and the cost/schedule change logs, add the Export Change Details step action to your workflow Complete step before the Apply Schedule Changes, Apply Cost Changes, and Remove Temporary Data step actions.
For steps, see Export the Change Details Report And/Or Change Logs. The information is exported to an Excel spreadsheet and attached to the workflow form Links tab.