Unable to assign Adhoc approver to BPM Task

Approvers are unable to adhoc route to another approver when reviewing a BPM Task on their worklist. We have the Task Actions on the Access tab for the BPM Task set to Adhoc Route = Assignees; Owner and Reassign = Admin; Assignees; Owner. We also have The Assignment and Routing Policy options on the Configuration tab set to "Allow all participants to route task to other participants", "Allow participants to edit future participants", and "Allow initiator to add participants". However, approvers are not seeing the option to adhoc add another approver when they open the task.