As a Responsible User of a Task, if you are trying to sign off on a Change Request Task but you cannot see the checkmark icon it is most likely because the Change Request has not yet reached the Implementing status.
For example, while a Change Request is in the Under Signing by Approver status, on the Change Request Details Page, you will not see the checkmark icon in the Actions column:
On the other hand, while a Change Request is in the Implementing status, you will see the check icon in the Actions column in the Change Request Details Page:
Relevant for: Administrators / Managers / Regular Users / Read-Only Users.
Please note: Only the users responsible for executing the Change Request Task will see the checkmark icon next to the Task they are supposed to sign off on.