Portal filtering sometimes

I have a portal that I use to display tasks that have been assigned to specific associates. Currently I filter them so that if the task status is "Complete" it gets removed from the portal list. This works fine.

Tasks::tStatus ≠ "Completed"

I also added a field to the tasks table, "parentProjectStatus" in hopes that I could filter out tasks that belong to projects that may have been cancelled or put on hold. The field is set to be equal to Projects:Status.

Tasks::tStatus ≠ "Completed" and
Tasks:arentProjectStatus = "Current"

The problem is that the filtering doesn't always work. If I go to my projects layout and change the status of a project and come back the tasks are still listed in the portal even though the field "parentProjectStatus" has been updated to show the new status of the parent project in the portal rows.

If I modify any field value within one of tasks and come back the portal has now filtered the results.

Any ideas?