Unable to select actions on performance document, actions are greyed out

The HR Specialist has selected a performance document, and would like to perform actions such as 'Change due date' and 'Move current task forward'. However these actions are greyed out. I understand why Reopen, Restore, Delete and Move task backward are greyed out. But Changing due date and move task forward should be available for selection as we have due dates entered already at template level and we are on the first task in the process flow. Any idea why this is happening?