This article will explain how to show all feedback items when they are hidden. You might need to use this if a filter has accidentally been added to the feedback grid which then hides your feedback. An indication that this would happen is shown below.
NOTE - The top message states that there are feedback items, but below it shows that there are none.
Use the "Clear Filters" button (shown below) to remove the filter that was put in place causing the problem.
The result will be that all feedback items show again: