Email Workflow approval is not updating Workflow Notifications

Hello and thanks in advanced for your collaboration with the following situation.

  There are a couple of users that receive a workflow email in order to either Approve, Approve and Forward, Reject Internal Sales Orders. When users click in Approve Link, the process seems to be completed however, the Internal Sale Order is still in In Process Status (Windows 8.1 is installed). When Checking Workflow Notifications the Status is Pending. The system is waiting for the user to enter to workflow, and proceed with the Notification. In other words whenever a user click in the email workflow Notification for approval this is not somehow updating the workflow notification reflecting the action.